MAKING TUBULAR FURNITURE RACTICAL9D ' MECHANICS EDITOR : F. J. CAMM MARCH 1948

IN THE GENERAL FITTING SHOP OF A BRITISH ENGINEERING FIRM (SEE PAGE 210).

PRINCIPAL CONTENTS

Making a Telescope Reflector Electric Water Heating Practice World of Models The Conundrum of Coal Ballistics in Nuclear Physics Trade Notes A Circular Saw Bench Printing Box and Safelight Cyclist Section I/ reetWimeee/44e t&O,e AlemamfA,"; ell 99

A Cl/P FOR DRAWING BOARDS

11°3041

People are amazed when they learn of the variety Gf CLIPS we make - steel clips, bronze clips, stainless clips, big clips,small clips...clipsinevery conceivable shape and pattern ...clips for every possible use. We can make to print or specification or our Research Department can design a clip for that particular job of yours. Over 92 years of clip -making is at your disposal. k,C,) HERBERT TERRY & SONS LTD. REDDITCH London, Birmingham, Manchester March, 19 48 NEWNES PRACT CAL MECHANICS 181

66 ff BALL THE ZYTO TEN MOTORISEDBEARING SAW BENCH For crosscutting, ripping, grooving, mitre- ing,bevelling,etc. Takesloin.saw. Spindlerunsinheavyball -bearings, parallel rise and fall Table with rackfeed and 'canting for bevelling, etc.Right and lefthand mitreslides,approved saw= guards. Vee belt drive, built-in dust chute, swivel motor base. Supplied A.C.200-220., 230-250. Three-phase 400-440. Direct Current. Price and illustrated leaflet free and post free on application.

66 THEZYTO 3" CAPACITY Threeof -overFIFTY ! * We now offer from stock in Northampton, London and Manchester, a PRECISION BENCH DRILLING MACHINE range of over Fifty SHIPS' FITTINGS, in two sizes (;in. scale and ;/"Iiiin. 3 jaw, self centring chuck, capacity o- r scale), beautifully finished and nickel plated and ready for easy assembly. * THE MARINE MOTOR for motor boats up to I metre works on dry 3 -speeds, drills to centre of 6".Max- battery or accumulator, 6-8 volts, weight IS ozs.Price 3716. imum distancebetween chuck and * SCALE MODEL STANCHIONS in hard brass, unequalled for accuracy and strength-scale (,in. to I foot. base,so". Size of table,5" diam. * For particulars of these and other models now available, write now for List This can be swung clear of work. (SFI12), priceII-. Size of basemachined,5i"x5". Write also for (MYI12), price 6d.' How to Sail your Model Yacht.' Price Complete, £10/17/6 Ex Stock. (L/12) price 6d.' Stock List of Model Supplies.' With 3 -jawkeytypeself -centring Please quote our reference for each booklet. chuck, £11/18/6. BASSETT-LOWKE LTD. TOOL AND MACHINERY NORTHAMPTON S. TYZACK & SON LTD. SPECIALISTS London Showrooms :112, High Holborn, W.C.2. 341-345 OLD STREET,LONDON, E.C.1 Manchester :28, Corporation Street. Tyzgar, Frnsquare You are invited tovisit our London or Manchester branches, where our Telephone: Clerkenwell 4004 56 Telegrams : Staff isat your service.

IE--THE LARGE LIP.- EASY POURING

JOHNSONPLASTIC DEVELOPING DISHES

THESE deep dishes are easy to empty without splashing or dribbling. Embossed ridges raise prints and prevent accumulation of sediment. Light, strong and not liable to get chipped or broken. Hard, black plastic can be kept clean, bright and free from stains. Impervious to ordinary Whatever your soldering job, in your home chemicals.They can be obtained from all photo- or workshop, you will prefer to use Ersin graphic dealers and will be invaluable to amateur MulticoreSolder. No extra fluxisre- photographers who develop their own negatives quired.Multicore isthe simple and pre- and make their own prints. cision method of making sound soldered joints for all household purposes. Just applyitsimultaneously with the soldering 4/ x 31 ( 9 x 12 cm.), 1 -in. deep iron; the three cores automatically provide x 61 (13 x 18 cm.), I7, -in. deep correct proportions of flux to solder. 61- x f4 (18 x 24 cm.), 2 -in. deep Workshop Sizes 4/10 - 6/9 each JOHNSONS OF HENDON MULTICORE SOLDERS LTD., CARTON MellierHouse, Albemarle Street, London, W.I. PHOTOGRAPHIC CHEMICALS AND APPARATUS shown above Tel.: RE Gent 1411. 182 NEWNES PRACTICALMECHANICS March, 1948 I.C.S. TRAINED MEN Tools" YOU Should have The "AEROMATIC" arein Greater Demand Soldering & Brazing Torch A general purpose low pressure gas torch with high than Ever-Maximum production pressure performance. Only needs connecting to any depends onhigh technicalskill,such ordinary gas tap. No maintenance, no adjustments, no lighting back. asthat acquiredby I.C.S. Students SIMPLE - FOOLPROOF - EFFICIENT TENS OF THOUSANDS MORE Sent complete, asillustrated, on receipt of 37I6d. with order. TRAINED MEN ARE URGENTLY NEEDED NOW-BUT THERE IS The" CRYSTAL" NO WORTH -WHILE PLACE FOR Spray Gun THE UNTRAINED The ideal tool forallpainting jobs from a model to acar. Also for house painting, distempering, etc. Connected to any standard Ambitious men everywhere have succeeded through vacuum cleaner it will produce professional I.C.S. Home -Study Courses.So also can you. results without mess, waste or effort. The man with an I.C.S. Training in any one of the subjects The " Crystal " Spray Gun will be forwarded by return,postfree,onreceipt of 751 - listedbelow knowsitthoroughly, completely,practically. with order. N. B. Please state make and Andheknows how to applyitinhiseveryday work. type of cleaner when ordering.A special connector, desirable withal! TRADE Accountancy Diesel,Engines Motor Engineering and essential with some ENQUIRIES Advertising Draughtsmanship Motor Mechanic cleaners, is availableat316 INVITED Aeronautical (State which branch) Motor Vehicle Elec. .3 extra. Engineering Drawing Office Practice Municipal Eug, Air and Vacuum Electrical Engineering Plastics 0/01Dept. P.M. Brakes Electric Power, Light- Plumbing HIBMON/ Air -Conditioning ing, Transmission, Quantity Surveying otympi DOMESTIC SUPPLY COMPANY Architecture Traction Radio Engineering Architectural Drawing Eng. Shop Practice Radio Service Eng. 341, REGENT'S PARK ROAD,LONDON, N.3 Auditing Fire Engineering Refrigeration Boiler Engineering Free -Lance Journalism Sales Management WE AREEXHIBITING (Near Finchley Central Statics) FINchley 5190 Book-keeping Fuel Technology Salesmanship Building Construction Heating and Ventilation Sanitary and Domestic Building Specifications Hydraulic Engineering Engineering Business Training Hydro -Electric Sheet -Metal Work Business Management Illumination Eng. Short -Story Writing Carpentry Industrial Management Steam Engineering Chemical Engineering Internal Comb. Eng. Structural Steelwork Chemistry, I. & 0. Joinery Surveying A Wise Investment ! Civil Engineering Lettering (State which branch) Clerk of Works Machine Designing Telegraph Engineering Coal Mining Machine -Tool Work Textile Designing Colliery Examiner's Marine Engineers Welding, Gas and Elec. S. G. BROWN, Type K ' Colliery Overman's Mechanical Drawing Woodworking Moving Coil Headphones, with Commercial Art MeehanicalEngineering Woollen and Worsted the following. outstanding Concrete Engineering Mine Surveying Manufacturing characteristics,supplythat Cotton Manufacturing Mining Engineering Works Engineering H igI.FidelityReproduction And most of the Technical. Professional, Commercial and Civil Service also C.I.I. Elements of Nat. Insurance. demanded for DX work, Exams. ; monitoringand laboratory students preparing for Examinations are coached till successful) purposes, etc. needtechnicaltraining,ouradviceon any matterconcerning If you NOTE THESE CHARACTERISTICS. yourwork and yourcareeris yoursfortheasking-free and without Let us send you full information regardingthesubject in which you obligation. D.C. RESISTANCE, 47 Ohms. are specially interested.DON'T DELAY.Make ACTION your watchword. The successful man DOES to -day what the failure IMPEDANCE, 52 Ohms at1,000 c.p.s. INTENDS doing to -morrow. Write to us TO -DAY SENSITIVITY,1.2 x 10-12 Watts at Ikc. Dyne/cm". Use this Coupon PRICE £5.5.0 PER PAIR INTERNATIONAL CORRESPONDENCE SCHOOLS LTD Supplies now available. Dept. 95, International Buildings, Kingsway, London, W.C.2 Order from your Local Dealer. For details of other Please send me particulars of your Courses in TYPE ' ' S.G. Brown Headphones (prices from 25/-to 60-) ask for illustrated Brochure Name Age Descriptive Literature on request. (USE BLOCK LETTERS) " P.M." Addrcs HEADPHONES WHICH UPHOLD BRITISH PRESTIGE

Addresses for Overseas Readers Australia :140, Elizabeth Street, Sydney. 'Phone: ACOrn502 I. Egypt :40, Sharia Malika Farida, Cairo. India :LakshmiBldgs.,Sir Pherozsha Mehta Fort, Bombay. VICTORIA ROAD, NORTH ACTON, LONDON, New Zealand : 182, Wakefield Street, Wellington. ICS South Africa :45, Shortmarket Street, Cape Town. March, W48 NEWNES PRACTICAL MECHANICS 183

0000000000 trio0000000 ...... TWO MODELS Now OFIIIIE rmirilaitgraiouniori;. 000000

ifry 31c CINs ;111511-1:1 Here'sgood news :the D.L.P.Eight -in -one oo Ogr I Air -sty w,,, 10! Tool is now available in two models --the D.L.P.

-Mum xwatampbilip Major and the D.L.P. Minor (the D.L.P. Major is larger).Eight different tools in one compact unit that will handle scores of different jobs. clin-PURPOSE "VOL Manufacturers of IN01.46 DRAWING and coot,Shardened jaw. grips. vice with reversible hardened Parallelvice with bender SURVEYING 2 Pipe and strip Tube, ,,:alpainvid INSTRUMENTS 34 C.ubbele',and rod co 5 Flat mmachine' 6 Screwingstepper. 7 Cable SLIDE RULES El Punching.

D.L.P. Major DRAWING MATERIALS Has a Sin. Parallel Jaw Vice. Screw -cutting up to2in. diameter. Fitted with geared, detachable handle.

DRAWING OFFICE Istr,li D.L.P. Minor 000 13 STATIONERY Parallel Jaw Vice. Screw -cutting upto

Whit,in. gas, I in.conduit.

Both machines beautifully made and finished. A G T -El- 9RN T.? N. LTD Write NOW for illustratedleaflet 4to HAMILTON MOTORS, LTD. 41 G R.T.IIDEIT. MANCtiffTER 3. 466-490, Edgware Road, London, W.2

Tel : PADdington 0022.

THE "FLUXITE QUINS AT WORK " You'rein afine tangle, grinned EE. " What on earthisthatthing s'posed to be ? A lampshade, by gum ! fight You need FLUXITE, old chum,

Or you'll beina worse mess, SUF.,k.s. strikes me." the For all SOLDERING work-you need FLUXITE-the paste flux -with which even dirty metals are soldered and " tinned." For crisis the jointing of lead-without solder ; and the " running " of white metal bearings-without " tinning " the bearing.It is suitable for ALL METALS-excepting ALUMINIUM-and can be used fC4 with with safety on ELECTRICAL and other sensitive apparatus. With Fluxite joints can be " wiped" successfullythat are impossible by any other method Used for over 40 years in Government works and by leading ItAGS engineers and manufacturers.Of all Ironmongers-in tins, SAV 10d., 1/6 and 3/-. What'swrong AiTO CYCLISTS! For stronger wheels that withkeensaving lirwill remain round and true, here's a time - anyway ?It's good for us all and tested tip.Tie the spokes where they cross good for our country, too.So let's with fine wire AND SOLDER.It's simple- with FLUXITE-but IMPORTANT. get cracking Withevery sixpenceand shilling we can muster. Ten shillings ALL MECHANICS WILLHAVEN THE "FLU X 1TE" buysaSavingsCertificatethat GUN puts"FLUX- ITE" where you becomes 13/- tax free in ten years- want it by a simple pressure. FLUXITE SAVE THE BANK WAY no bad bargain! And the maximum Price 1/6 or filled holdingisa thousandcertificates. 2/6. Your Bank will tell you about a new IT SIMPLIFIES ALL SOLDERING simplewayofbuying National Buy through your Bank or from a Savings Certificates-either by single Write for nook onthe ART 'OF "SOFT" SOLDERING and forLeafletso Post Office or Savings Group. CASE -HARDENING STEEL and TEMPERING TOOLS withFLUXITE. purchase or regular investment, Also on WIPED JOINTS.'Price Id. Each. operated free of charge to costume:. FLUXITE LTD., Dept. P.M., Bermondsey Street,S.E.I Issued by the National Savings Cohunittre 184 NEWNES PRACTICAL MECHANICS March, 1948 METERS at a ONCE - IN - A - LIFETIME' PRICE RATCHET SPANNERS Brand new ex Admiraltyand R.A.E. milliammeters, voltmeters, and ammeters, offered at a price HUGE demand enables us to far less than their manufacturing offer " Leytool " Ratchet Spanners at cost. Never to be repeated priceslittleabovethosepaidfor A verycomprehensiverange as follows: ordinary good quality spanners. They 0-1 mA moving coil D.C. 21in. 15/11 0-2.5 amp. R.F. Thermo- save time and money because they 21n. 10/- couple ... 2in. 7, 3 work faster, operate more easily, and 0-30 21in. 619 0-4 amp. R.F. Thermo-. get into those inaccessible places where 9-50 21in. 71- couple ... 21in.101 - 0-40120 2in. (with shorting switch) ordinary spanners will not go. 7/- 0-10 amp. R.F. Hot Wire 5in. 30,- They are a sound British engineering 0400 0-12 amp. R.F. Thermo- job, made of carbonchromesteel, shorting(within'sjiTet) couple ... 3in. I0'-

0-150 hardenedalloverandnegradised. 21n. 7/3 0 -40v.Moving coil D.C. 2in. 7,- 0-500 211n. 7/3 8 0-300v. 2in. 7,- Available in standard sizestofit 0-1500 71.8 0-15v, iron A.C. 211n. 10 - t5onutsizesinB.A.,Whitworth, 0-10 amp. 21in. 7/6 0-20v. 21in.10/ B.S.F.,S.A.E.,Metricandsquare. 0-14 ., iron, ironclad 5in.37/6 0-1500v. Electrostatic 3110.27:6 Special sizes made to order. 50-0-50 coil D.C. 2in. 7/6 0-2000v. 3in. 27, 6 150-0-3000 mA. 3,in 15i - Also available, Mechanic's Set of5 0-.5 amp.R.F. Thermo- OR OUR SELECTION OF 6 ASSORTED " Leytool " Ratchet Spanners in Canvas couple ... 2in. 71 METERS FOR 35/- Wallet. 2 -VOLT VIBRATOR PACKS. A miniature 2v. power supply to operate any normal WriteforIllustratedLeafletgiving set from any 2v. L.T. ! As designed for the Canadian " Walkie Talkies."Size of unit. sizes and prices. bin. x 31in. x 41in.Output 90v. or 180v., 35 mA. 1.5v. L.T. As new. ONLY 52/6 (Carr. and pke. 2, 6). Alternatively supplied in carrying case at 55/- (Carr. and pltg. 3/6). Spare Vibrators.2 v. 7 pin. 9/8. Spare Fuses (10 amp.), 6d. each. Two accumulators 15/-. FOOT CONTROL SWITCHES. A very heavy duty Riot switch able to carry up to 600 watts.Press for"ON."Precision machined of solid brass. A " Third hand " for 200A to 4/400/5"FORTHE MOST UP-TO-DATE only 22/8 (carr. pd.).Ideal for control of machinery, dark room, etc., etc. REMOTE CONTROL UNITS. A Canadian made wireless remote control unit, used to send and receive messages over wireless equipment from either of 2 distant locations. AND EFFICIENT Complete with microphone and headphones in transit case, and fitted with hand generator and bell set, morse key, etc. ONLY 39;6 (Carriage pd.). HAND MICROPHONES. Brand new moulded bakelite hand microphones, with switch DESIGN incorporated. Complete with lead, etc. ONLY 3/6 (Post 9d.). MINIATURE SPIRIT LEVELS." Brand new brass cased spirit level, with 2 fixing All Leytoolsareentirely holes on base. :ibis. between fixing centres.ONLY 1/11(Post 5d.), OR 3 for 5/-. Precision Ratchet Universally 1 -bladed original and patented de- Watch next month's announcement of the Burgoyne Solder Gun. Hand Drill Spanners Jointed Pocket signs.Write for illustrated (Mechanic's Socket Screwdriver leaflets. MAIL ORDER SUPPLY CO., Set) Spanners Dept. 1'.M., Export Agents in all countries. Names and Addresseson application. LEYTONSTONE JIG & TOOL CO., LTD., High Road, Leyton, London, E.IO 24, NewRoad,London,E.1. Telephone :/EYtonstone 5022-3-4 Stepney Green 2760-39011

11/111101/11111111111111111W

Start work onit 4 / TYPE M L7 now and be ready for I,"HEAVY DUTY LATHE the spring The finestLatheinitsclass. Extensive The Merlin " rangeof 36" M. Y. A. restricted accessories. class

MODEL YACHT Weare OFFICIAL STOCKISTS of. plans and instructions " PERSPEX "and" CRINO- TI-IENE," carryinglargestocksfor immediate delivery at CON- 816 MYFORD ENGINEERING COMPANY LIMITED TROLLED PRICES. BEESTON NOTTINGHAM 'Phone: 54222(3 lines) POST 6d. " PERSPEX " in Ciear and Coloured, 07.1498 .nflatsheet fromI/16intofin. THESEplans consisof three large thickness. sheetsofdrawingsfullyannotated and two sheets of instructions.Set out with all the thoroughness and attention Shows the way to TECHNOLOGICAL SUCCESS SmallConsumers, Hobbyists and todetailforwhichModelcraftare prototype Plastic Engineers, come to renowned they give you all you need IN ENGINEERING BRANCHES AND PROFESSIONS us withyourenquiries. to create a potential cup winner.Two alternative methods of hull construction Throughout industry in every country, are described. but particularly in Great Britain, technologicalsuccess has become the Magazine Az List No. 5 basis requiredforpersonal success. Send for Price List. At press now.Gives details of over 45o Write now forthisgreatguideto plans, plan books, kits and accessories as careers in Engineering covering well as articles, notes and hints. We are DE 10 SUCaSS: Mechanical,Electrical,Chemical, doing our level best to keep up to the Production,Aeronautical, Auto- demand for the magazine, but the only mobile, etc., and which shows how to PLASTICS way to be sure of your become A.M.I.Mech.E.,A.M.I.E.E., copy is to he put on the POST A.M.Inst.C.E.,A.M.I.Chem.E., etc., (MCR.) LIMITED. subscriber list or to get FREE in which and other engineering institution 1/ examinations T.I.G.B. yourmodelshopto 4/6 for home -study II, WH ITWORTH ST., reserve your copy every professional feinii:ig studentshavegained OVER FIFTY quarter. fourissues FIRST PLACES, to - acd Cireqg'7,511, MANCHESTER. I. Modelcraft Ltd. talneegustry The Professional Enginzaring Tutors, Phones: central0272 't I THE TECHNOLOGICAL INSTITUTE and1725 4 1 77(L) Grosvenor Road OF GREAT BRITAIN, London, S.W. I 218, Temple EstHouse, London,E.C.4. March, 1948 NEWNES PRACTICAL MECHANICS 185 HIGHSTONE UTILITIES PELMANISM CRYSTALSETS Our latest Model is a REAL RADIO For Courage and Confidence RECEIVER, which isAttest witha PELMANISM is useful in all CRYSTALPERMANENT the affairs of life.That is D E T 11 CT 0 R. WRY NOT HAVE As outstanding recommendation to A SET IN YOUR those who wish to make the best OWN ROOM OR AS A STAND-BY of themselves in their occupations, -9/6, post Od. in all their recreations, and in their DE LUXE RE- CEIVER Inpol- social and cultural relations. ished oak cabinet. 18.6, post 1/-. Every line written in the'Pelman Spare Permanent Detectors, 2/- each.when or- Course isdirectly applicable to dered separately, 2/6.Postage, 3d. .0003 Pre-set Condensers, 2/-, post 3d. Headphones. some aspect of human life and brand new- S. G. Brown, (INC.... etc4 15/-, Mk conduct.The intention of every and super -Sensitive, 30/. a pair, postage 64, word in the Course is to , make MICROPHONES clear to men and women the means Just, the thing for imprrmptu concerts, room to room communicaLlon, etc.Bakelite table model, by which they can develop their 6/9'; Suspension type, 8/8.Poet fid.Super Model powers to the fullest extent so that onstand, 1.218. Fittinginstructionsincluded. Mike Buttons.2/6. Transformers, Public they can live more happily and be Address Transverse current Mike, 371, post 1/-. more successful-so that, on the All microphones have transformerincorporated. one hand, they will make and use saufs0tutli14 MORSE KEYS AND BUZZERS occasions for profit and advantage Standard size keys wired to work Buzzer or Lamp. 3', post 6d.No. 3 Heavy Duty Double Coil, 419, and, on the other hand, be at ease post 3d.Plugs (for Jacks) with short length of in any company.Both conditions twin ilex, 1/6, post 40. are necessary to completeself- BELL TRANSFORMERS respect and a full life. These guaranteed trans formers work from any Remember-Everything you do is A.C. Mains, giving 3,5, preceded by your attitude of mind. or 8 volts output at 1 amp., operate bulb, Pelmanists are not left to make buzzerorbell. Will the applications themselves.An supply light in bedroom or larder, etc.PRICE 7/-. Post 60. experienced and sympathetic in- ONLY HEAT REQUIRED TO COMPLETE THE JOB BELLS forusewitheitherthe structional staff shows them, in above or batteries, (1)..Post ed. exactdetail, how to apply . the OBTAINABLE FROM ALL IRONMONGERS SOLDERING IRONS principles of Pelmanism to their Established1834 Adjustable RR,allpartsreplaceable andfully guaranteed.200/250 v., 60 watts, 9,43; 150 watts, own circumstances and aspirations. 12/6,post6d.Smalr SolderingDons,foruse Thus every Pelman Course is an on gas, 1/4.Post 4d. Resin -cored solder for easy soldering, 6d. packets, or Ilb. reels, 6/-.Postage individual Course.Over and over SIR Wm. BURNETT X, CO. (Chemicals)LTD. extra. again our correspondents say in. GREAT WEST ROAD, ISLEWORTII, MIDDLESEX SparkingPlug Neon Testerswithvest effect, " I feel that this Course' pocket clip,2/9, 3/3, was prepared for me, and me or with gauge post3d. BELFAST TORONTO MELBOURNE only." Substantially thisisso, Ex.R.A.F.2 -valve (2 -volt)Microphone JOHANNESBURG WELLINGTON N.Z. Amplifiersas used in plane inter -coin., for theinstructional notes and inself-contaiRed metal case,whichin lettersofadviceareentirely Smee's turn is housed in a useful wooden box, personal to the individual;they 10/- each Peas valves), post1/-. are for him or her only. Field Intercommunication Sets,ready for use, complete with ringing hand generator, Half fees for serving and ex -Service bell, signal lamp, morse key, relay and members of His Majesty's Forces all necessary jacks and switches.Con- (Apply for Services Enrolment Form) MAKE THESE YOURSELF tained in a strong metal case with circuit diagram.25/-each,carr.2/6 ; 47/8 Itmay bethatfrustration, .0 pair, carr.2/6.'New handcomb sets, for AND MAKE i -fim- use with above,7/6d,post6d. Ex-G.P.O. or anxiety may come your way ; ,t.,..,1 i':-P Telephone Bells and Box,5/-,post Td. unfortunately,itdoes,then it, 4 Telephone hand generator, with handle, 9/6, 4/6, with a mind trained to meet the (MONEY ! ") tq ' 1 post 1/6.Belt, post .6d. vitgaries and turmoil of everyday LA IL.. Is, Hand Microphones,with switch in handle, life, .you will be in a position Withourtoy -castingmouldsand and lead,4/-.Similar instrument moving Toy Soldiers, fik-drying enamels, making these and coil,8/-,post8d. speedily to overcome these Cowboys tY Indians, hindrances andset -backs; and "Wild & Farmyard other models becomes a really profitable Headphones,reconditioned and in good eventually be free to devote all Animals, pastime, or fascinating hobby.Full in - order,5/6a pair, post6d.(better quality, Aeroplanes, struct ions with every first order.,Send 7/6epair.) your mental energies to attain a Ships, Cars, etc. s.a.e. for fulldetails. Write to -day ! New Headphones, 10/- a pair,post6d. fuller,richer and happierlife. Balanced armature type (very sensitive, .The domindnt aim for every anti very suitable for use with crystal sets), PROGRESS TOY CO. LTD. 12/0a pair, post6d. NewSingle Ear- man and woman must be to show pieces, 3/6. armature type,5/-,post acourageous,confident,well- Dept. P.M., KIRBY ROAD, BLACKPOOL, S.S. 4d. Headphoneswith moving coil mike, equipped mentalfront. The Telephone : BLACKPOOL 759 15'-.Similarphones with throat mites, 12'6.post8d. Headphone cords, 1/ - general effect of the training is to pair, post3d.(24per 100).Replacement induce an -attitude of mind and a bandsfor headphones, 1/-, post4d.(24 personal efficiency favourable to per 100).Wire bands, 6d.per pair ; 2 the happy management oflife. ). YOU RotaryTransformers, 12 v. D.C. input, Take Up Pelmanism Now in sound -proof cabinet, for Car Radio, etc.. The Pelman Courseis.fully will also light two 25 w. lamia( in series. explained in " The Scienceof can become a first-class 22/6each, carr.2/6. Success." The Course is simple aaadmansloin.P.M.Loudspeaker in cabinet with volume control and traits. and interesting and takes up very former,35/-,earn 2/6. little time.You can enrol on the RADIO ENGINEER METERS, GOOm.a.,3in.,m/c.,15/-; most convenient terms. The book We arespecialistsin will be sent to you, gratis and post Home -StudyCourses,nRadioEngineering, Double reading 40/120 m/a., 2in.,m,/c., Servicing, Transmission, Television, Mathematics and Radio Calculations. 8/-;20 amp., 2iin., 7/6;15 volt free, on application _to -day to : m/c.,9/6 ;30 amp., Gin., mil Switch- Post coupon now board mounting, 35/-;0,000v.3in., PELMAN INSTITUTE for free booklet T. & C. RADIO' COLLEGE, rule.,23/10.All postage extra. (Established over 50 years), andlearn how NORTH ROAD, PARKSTONE, DORSET. SEND ld.S.A.E. FOR ILLUSTRATED 130, Norfolk Mansions, you can qualify LISTB.P. OF USEFUL ELECTRICAL for well -paid ACCESSORIES. Money refunded if not Wigmore Street, London, W.1. employment or I Please send me freedetailsof yout Home -Study completely satisfied.I.etters only.Please Callers welcomed. profitable spare - I Coursesin Mathematics, Radio and Television. include postage ; any excesswillbe PELMAN (OVERSEAS) INSTITUTES : PARIS, time work. refunded. 176, Boulevard Haussmann, AMSTERDAM, Name 1 Damralc, 68. NEW YORK, 271, North Avenue, New Rochelle.MELBOURNE, 396,Flinders (Post coupon in i Address Lane. DURBAN. Natal Bank. Chambers (P.O. unsealed envelop- HIGHSTONE UTILITIES Box 1489). JOHANNESBURG, P.O. Box 4928. -Id.stamp.) 1 58, New Wanstead, London, CALCUTTA, 102, Clive Street.DELHI, 10, M:15 Alipore Road. sa.ss E.I I 186 NEWNES PRACTICAL MECHANICS March, 1948

PREPARE FOR COMPETITION -POW! As the Engineering Industry swings into its normal stride, the inevitable competition for the secure and well -paid posts will return.Itis the man who stands out from the rest because he is technically trained who will be in the happy position of taking over the more responsible, more secure, and better paidpositions." ENGINEERING OPPORTUNITIES " will show you how to get this all-important technical training quickly and easily in your spare time.This 100 -page book is full of valuable information and explains the simplest way of preparing for recognised Examinations.Among the courses described are : MECHANICAL ENGINEERING GROUP ELECTRICAL ENGINEERING GROUP A.M.I.Mech.E. Mining Practice A.M.I.E.E. Electricity Supply A.M.I.E.D. Estimating City & Guilds Electrical Meters City & Guilds Foremanship General Electrical Eng. Electrical Design General Mechanical Eng. Jig & Tool Design Alternating Currents Illumination Diesel Engines Viewing & Inspection Power House Design Installations *Draughtsmanship & Tracing Welding Traction Telegraphy Works Management Sheet Metal Work Mains Eng. Telephony Press Tool Work Maintenance Eng. Mining Electrical Engineering Pattern Making Metallurgy Foundry Practice Refrigeration WIRELESS GROUP A.M.Brit.I.R.E. Advanced Wireless COMMERCIAL ENGINEERING GROUP C. & G. Telecommunications Radio Servicing A.M.I.P.E. Cost Accounts General Wireless Television Commercial Eng. Languages Short-wave Wireless Sound -film Projection Eng. CIVILENGINEERING GROUP AUTOMOBILE ENGINEERING GROUP A.M.I.C.E. Mining Surveying A.M.I.M.I. General Automobile Eng. Inst. Mun. Engineer Road Eng. City & Guilds Garage Management A.M.I.Struct.E. Hydraulics Automobile Repairman Electrical Equipment M.R. San.l. Municipal Eng. Course High Speed Diesels City & Guilds General Civil Eng. Sanitary Inspector Structural Eng. Specification Reinforced Concrete AERONAUTICAL ENGINEERING GROUP Structural Design Railway Eng. Aero Engines R.A.F. (Maths.) Navigators' Licences Pilots' Licences Aeroplane Design SURVEYING ANDBUILDING GROUP A.R.B. Licences Meteorology A.R.I.B.A. Costing & Valuations F.R.I.C.S. Heating & Ventilating UNIVERSITY DEGREES A.M.I.H. & V.E. Clerk of Works L.1.0.13. Surveying & Levelling London Matriculation University Entrance F.A.I. Building (all branches) School Certificate Intermediate B.Sc. Our Diploma is accepted for Graduateshipof the Inst. of Engineering Draughtsmen and Designers. WE DEFINITELY GUARANTEE 44NO PASS -NO FEE " If you are earningless than f10 a week you cannot afford to miss reading " ENGINEERING OPPORTUNITIES " ittells you everything you want to know to make your future secure, and describes many chances you are now missing.In your own interest we advise you to write for your copy of this enlighten ng guide to well -paid posts NOW-FREE and without obligation. BRITISH INSTITUTE OF EXCATERING HOROLOGY 410A, SHAKESPEARE HOUSE, 17, STRATFORD PLACE, LONDON, W.1 THE B.I.E.T. IS THE. LEADING INSTITUTE OF ITS KIND !N THE WORLD, March, 1948 NEWNES PRACTICAL MECHANICS 187

SUBSCRIPTION RATES (including postage) Inland 10s. 6d. per annum. Abroad 10s. per annum. PRACTICAL Canada 10s. per annum. Editorial and Advertisement Office :" Practical Mechanics," George Newnes, Ltd. Tower House, Southampton Street, Strand, ).4/.C.2 'Phone : Temple Bar 4363 Telegrams : Newnes, Rand, London. Registeredat transmissionby MECHANICS the G.P.O. for Canadian Magazine Post. Owing to the paper shortage "The Cyclist," "Practical Motorist," and "Home Movies " are Copyright in all drawings, photographs and articles temporarily incorporated. published in " Practical Mechanics " is specially reserved throughout the countries signatory to the Editor: F.J. CAMM Berne Convention and the U.S.A.Reproductions orimitationsof any of thesearetherefore expressly forbidden. VOL. XV MARCH, 1948 No. 173

FAIR COMMENT BY THE EDITOR What is Craftsmanship ? THE Hallmark of workmanship and manu-Workman's Amenities standard of fidelity was stressed by Sir Ernest facturing excellence is epitomised in the THIS state of affairs does not exist to -day.Fisk, Managing Director, Electric and Musical words " British Made." Goods made in The working week has shrunk, and wagesIndustries, Ltd., in an address before the this country arc eagerly sought all over thehave expanded.Men do not start so earlyRoyal Society of Arts in London recently. world. Those goods are thesilentin the morning, nor work so late at night. Explaining how the frequency distribution ambassadors which can make or break theIt is a five-day week instead of a five -and -a -of these irregular non -repeating wave -forms reputation of this country asa nation ofhalf -day week.There are holidays with pay;determine the tonal character of a particular craftsmen.No oneplannedtheBritishthe conditions under which men work havesound, Sir Ernest Fisk, who was lecturing on Empire, and in these days of planning wheregreatlyimproved.Thesocial lifeof thethe developinent of sound recording and interestiscentred on the reward and anworkers in the factoryisthe concern ofreproduction, revealed thatthese transient increase of the reward, rather than on com-special personnel.There isMusic Whilepulses were known to extend well up to the manding that increase by improved skill andYou Work, wageincentives,andothertop limit of human hearing and even beyond craftsmanship, it must not be forgotten thatrewards to coax the worker to do what he isit into the supersonic range. more than ever isit necessary for Britishreally paid to do.His health is also guarded Sir Ernest Fisk then disclosed that for the goods to be made in accordance with theby clinics within the factories. first time in the history of Sound Science, tenets laid down by the early English crafts- In spite of all these improved amenitiesfrequencies of up to20,000cycles per second men.Their lives were wrapped up in theirthere isstill dissatisfaction, and I think itwere now being recorded on gramophone work.They toiled for the love of it.Nocan be traced to the fact that the desire for therecords produced by his organisation. effort was too great in order to improve thereward has become greater, in fact, has over- In terms of electrical reproduction, this quality of their goods, nor were they greatlypowered the desire to become qualified formajor development in the science of sound concerned about shorter working weeks. the reward.For it cannot be denied thatrecording and reproduction means that every In those old days when a master tookcraftsmanship, in thAe days of specialisation,note and every tonal characteristic detectable apprentices who wereinitiatedintotheisdeclining.Itisan overworked word,by the human ear in an original performance mysteries of a particular craft, men toiledand is falsely used by many to describe theircan now be heard with equal fidelity indirectly from six o'clock in the morning to six or later incrude work.To -dayitismostdifficult,off a gramophone record. the evening.They had only s.J days per weekhowever much you pay, to get a really good job of work done.The higher prices do not While the upper frequency response limit off,and Bank Holidays.There wasno of the human earisa factor that varies summerholiday.Incidentally,thewordcarry higher skill. enormously not only with theindividual mystery is a corruption of the word mastery, Craftsmanship has been replaced by vanitybut according to age, very few people indeed so that apprentices were initiated into thein the use of the word.An unskilled workmancan detect notes with frequencies higher than mastery of their craft. loves to call himself a craftsman, which is precisely what he isnot. Istill feel thatabout 15,000 or 16,000 cycles per second. The apprentice was bound by his indenturesto -day with all the opportunities providedThe main significance of the achievement of for seven years, and promised to absent him-for the advancement of skill and technicalrecording and reproduction of frequencies self from his master neither night nor dayeducation that some means should be foundas high as20,000cycles per second is the nor to suffer damage to his goods or propertyof classifying workmen. A man has not thesafety margin that it provides beyond the top during that time. right to call himself a craftsman because helimitofhumanhearingforsupersonic His parents had to pay £ too or more tohappens to be employed in a particular trade.transients affecting the character of sounds have him indentured, a solemn proceeding It was not easy in the early days of industrywithin the audibility range. takingplaceinasolicitor'soffice. Theto become a member of one of the Old Crafts - In striking contrast to Sir Ernest Fisk's solicitor read the articles over to him and,mans Guilds.You had to satisfy the mastersdescription and demonstration of this latest at the end, the apprentice placed his fingerof the Guild that you had served your time,recording achievement was his comprehensive on the seal and signed his fate for sevenand that you had become skilled at your trade.historical survey and demonstration of very years with the words, " This is my act andIt was necessary to produce references fromearly acoustic machines. These included deed." your master, and later your employers.Evenone of the very first hand -driven disc -type His salary was 2s. a week for the first year,then you were not admitted to full member-gramophones produced by Emile Berliner proceeding by annual rises of 2s. to 14s. a week. ship until you became a master man. towards the end of the nineteenth century At the end of the seventh year he could remain Vanity does not replace skill. A great deal(the origin of gramophone record technique on as an improver at a salary of £1 a week,of shoddy work is being turned out from ouras we know it to -day) and the slightly later which was paid in the form of a goldenfactories to -day.This state of affairs cannothorn model made worldfamous byits sovereign (good old days !), or the apprenticebe allowed to go on. We must improve theincorporation in the " His Master's Voice " was " hammered out " by the other appren-quality of the British products in view of theTrade Mark, which was painted by Francis tices beating noisily with hammers on vices,fiercecompetition we aresuffering fromBarraud in 1899. clanging spanners, and generally creating another countries who can produce under more Inhisconcluding remarks,SirErnest unholy din.The apprentice leaving in thisfavourable conditions than we do. Fiskmadereferencetotheaccusations way became a journeyman. He went from sometimes made that the gramophone industry firm to firm, improving hisskill, gainingA New Recording Development is holding back development of sound record- further experience up to the age of about 25, THE great importance of recording anding methods on film and on tape, etc., in order when he could consider himself a craftsman reproducing what are known as transientto protect their supposedly large investments or a master man. pulsesforthe attainment of thehighestin the disc manufacturing business.-F.J.C.

_J 188 NEWNES PRACTICAL MECHANICS March, 1948 Makingabin. Astronomical Telescope Reflector The Methods, Tests and Techniques Employed 'in the Production of an Astronomical Telescope Mirror

THE production of an accurate reflector 'ByT.J. MULLIGAN or with edges machined and square with die for an astronomical telescope is a task main surfaces; blankssuitable for use as which falls well within the capabili- The magnification depends upon the dis-grinding tools are also supplied. These blanks ties of the amateur handyman; an efficienttance of the principal focus from the surfaceare obtainable with a thickness of one -sixth mirror can be made at home, the only equip-of the mirror and the magnification factorof the diameter. ment required being two glass discs and the of the eyepiece.The size The abrasive used is carborundum powder, abrasives, polishing materials and silvering of the telescope is deter-a good selection of grits being Nos. 70, 9o, chemicals. minedbythediameter 120, F, FFF, 400 and 600.These grits are When suitably mounted the reflector will and focal length ofthenot at all expensive, and can be obtained provide its constructor with hours of interest reflector-in other words,either from the local engineers' stores or from and pleasure in the observation of the moon, by its aperture. There arethe Carborundum Co., Trafford Park, Man- planets, stars and nebulx. obvious limits to the sizechester. of a home -constructed Rouge is required for polishing; two to The Telescope telescope : The focalthree ounces should suffice with oare.Jewel- Fig.x shows the arrangement of the opti- lengthshouldbesuchlers'rouge canbe obtained from watch- cal components of a reflecting telescope; it that the eyepiece is com- makers' suppliers and is quite often stocked will be seen that the concave reflectoris fortablyplacedfortheby chemists. situated at the rear end of the tube, and the observer's eye when the A small quantity of pitch is required for eyepiece fixed at the side, near the front end tube is in a vertical posi-securing the mirror disc to its holder.The of the tube.For the purposes of simplifica- tion. Afocallengthpolishingtoolsare made from pitchwith tion the eyepiece is depicted as a single lens, greater than thiswouldthe addition of beeswax. although inpractice a Huygenian type of make impossible the study eyepiece would be employed, which is com- oftheheavensdirectlyPreparations posed of two piano -convex lenses. above, unless a much more Since thegrinding operation will be a In this sketch the mirror is shown reflecting ambitious mounting werelengthy process, it is advisable to take extra light from a star or very distant terrestrial constructed,ofatypepains with the preliminaries. object; this light can be considered as being rather beyond thecapa- The grinding post is the first and most parallel, and would normally be converged to bilitiesoftheaverageimportant item; in this case the indispensable the mirror's prime focus " f,"there form- ing an image of the star or object. In this position the image could not be conveniently observed, so a prism " p "is interposed which diverts the focus to a point outside the tube where it can conveniently be inspected by means of the eyepiece " e." It will be appreciated that since the prism Fig. liesdirectlyin the path of the oncoming i.-Diagram light a shadow will be cast upon the mirror showing the optical of an area equal to that of the prism (since componentsofa theincidentlightisparallelthe shadowreflecting telescope. can also be considered to be parallel, ignor- ing diffractioneffects). This representsa amateur.In addition, loss of light, but the loss is negligible when,as the size and weight the area of the mirror is large in comparison ofthetelescopein- to the area of the shadow.In the author's creases,thestrength telescopethesilhouette of the prism was andmechanicaleffi- 0.525 sq. in., which is less than 2 per cent.ciency of the mounting of the area of the 6 -in. reflector-a negligible increasesinimport- The grinding process. amount. ance. The aperture decided uponrequirementisrigidity-it must be either DoWel Hole by the author was fit°, usingveryheavyor securelyanchored. The a reflector of 6 -in. diameter.author's post was a tree trunk which had and the tube -length a littleseen service as a chopping block; this was over five feet. screwed to the floor and made a stout grind- ing post.A heavy barrel, or even a stone Materials bird -bath might be suggestedaspossible Two glass discs are requiredgrinding posts.The height should be from of equal diameter, one forthree to four feet; the width of the top and the mirror disc and the otherbase should not exceed eighteen inches, to tobe ,usedasagrindingpermitofacomfortablegrindingaction tool ;these discs should bewhilst walking round the post. Tool Board of a thickness not less than The top board, which carries the glass tool one -eighth ofthe diameter.disc, should fit on dowels so as to be remov- A smaller thickness to dia-able for washing when changing over to finer meter ratio would be liablegrades of carborundum; this fitting is shown Door 4"Diameter Knob to flexure or deformation ofin Fig. 2. Wooden the reflectingsurface under A shelf or table should be situated conveni- Disc its own weight, thus causingently close to the post. This should be serious deterioration of imagecleared and covered with a sheet of news- quality.Blanks suitable forpaper; on it are placed a dish of clean water Mirror Disc Handle mirror discs can be obtainedand the tin containing' the first grade of car- from Chance Bros., Ltd., ofborundum grits. A place should also be Smethwick, either with edgesprovided in which to stand the mirror disc Fig. 2.-Grinding post and details of tool -board, mirror disc androughly ground to diameterin the intervals between grindings. handle. but not guaranteed circular, Next a position must be found in which to March, 1948 NEWNES PRACTICAL MECHANICS 189 stand the mirror disc upright when testingor the mirror discwill rock for radius of curvature; there will need to beat the end of each stroke, re a clear space of at least twelve feet in frontsulting in chipped tool edges of the mirror; the necessity for this will beand consequent scratches on explained when the procedure of testing for thesurfaceofthe mirror. radius of curvature is described. (Fig. 3.) Grinding powders should be kept in tins - The tool should be kept and clearly labelled; one grade only should moist enough to allow of easy be kept on the shelf near the post at a time.passage of the mirror over, Grinding the tool ; too much water on Illustrating. Throw" Of Stroke the other hand will result in The tool -board (Fig.2)isplaced on its dowels on the tool post ;the dowels shouldmuch ofthe carborundum be a snug fit-no movement of the tool canescaping over the edge of the be tolerated when grinding. tool. The correct propor- The disc selected for use as the tool istionsof carborundum and placed in position onthe tool -board andwaterarebestfoundby adjustable edgeexperiment. secured by means of the Grinding is continued piece ;apiece offelt placed beneath the tool disc will help to prevent rocking whichuntiltheharsh" gritty " might be caused by any unevenness in thesound has softened, and the mixture of grits and water " PockingCaused By Over -long tool -board. has become white with Stroke The whole assembly-tool, tool -hoard andpowdered glass.More car- tool-post-should be quite rigid, and incap- Pig. 3.-Illustrating the actions during the grinding operation. able of independent movement. borundum andwaterare A handle is required for the mirror disc,then applied to the tool, and as shown in Fig. 2.The underside of thegrinding continued. flameto appear upon thesurfaceof the 4in. wooden -disc, which should be quite dry, The rate at which the mirror grinds con-wetteddisc. The observer now retreats cave depends upon the pressure applied andslowly, moving the candle from side to side, is smeared with turpentine, and a little melted is unwise toand raising or lowering it when necessary to pitch poured over it; the holder is thenthe number of strokes, but it stood aside for a few minutes in an invertedattempt to speed up the operation by apply-keep the image visible. ing undue pressure or increasing the number At first the image of the flame will follow position to allow some of the heat to dissi- that is to say, pate.When ready for applying to the glassof strokes per minute.Intimate contact ofthe movement of the candle the pitch should be warm and sticky, butthe mirror and tool should be maintainedas the candle moves from left to right, the whilst grinding, and this is not practicable atimage will move from left to right also, and not too hot. vice versa. The mirror disc, which should be gentlya high speed which would result in the mirror As the distance from the disc is increased, warmed, smeared with turpentine, and therocking slightly upon its edge at the end ofthe image will increase insize, and even- pitch coated holder pressed against it, takingeach stroke ;this would result in a turned -tually apointwillbe reached where the extra care to set it as centrally as possible. up edge, which would be very difficulttoimage, instead of moving to and fro,will When these preliminaries have been corn - remove.Too much pressure upon the mir-appear and disappear; beyond this point the ror handle would pro-movement will be reversed, that is to say, duce a similar effect. -as the candle moves from left to right, the Two or three hoursimage will move from right to left. grinding will probably The point at which no lateral movement be required before thecan be seen can be taken as being the centre mirrorexhibitsanyof curvature, and is equivalent to double the appreciable concavity ;principalfocus. The distance from this it will be understood,point to the disc is measured. however, thatsince The focus aimed atisfive feet,so the theradiusof curva-radius of curvature will require to be ten ture aimed at is soft., feet. the amount of depres- First tests should show the radius of cur- sionvisiblewillbe vature to be well over this figure ;so grind- quite small. ing should be recommenced and continued A straight -edge laidwith occasional intervals for testing until the _acrossthediscwilldesired curvature is very nearly attained. provide a rough check If the test shows that the radius of curva- upon the progressture is too small, the concavity can be re- being made ;after anduced by reversing the grinding positions of hour's grinding a smallthe mirror and tool discs, the mirror being gap will be visible inplaced upon the tool post and the tool disc Using the pitch polishing tool during the polishing process. the centre of the disc.stroked across it. Grinding is con- When the radius is found to be not more plated, the grinding operation can commence.tinued with 7o carborundum until the gapthan six inches more than ten feet, a change- The tool surface is wetted with a medi-appears to be alittle' less than one thirty-over is made to a finer grade of carborun- cine dropper full of water, and about a tea-second of an inch.The mirror can thendum. spoonful of No. 7o carborundum powderbe rinsed clean in preparation for the test The mirror disc andits holder arefirst applied. Themirrordiscis similarlyto determine the radius of curvature. thoroughly scrubbed so that not a speck of wetted, and laid on to the tool. the original 70 grit remains ;the tool disc The grinding operation is carried out asTest to Find Radius of Curvature and its base are removed from the post and follows : the mirror discis _stroked back- ' Theradiusofthecon- similarly scrubbed. wards and forwards across the centre of the cave surface could be tool in a direction directly away from theobtainedbymeansof a operator ; on the completion of each strokespherometer, but theoptical the mirrorisrotated about 20 deg. As methodcombinessimplicity the strokes are made,the operator walkswithastandard of accuracy slowly round the post, so that no two strokes whichisadequateforthis followexactlythe samediameter. (See stage of the operation. Fig. 3.) The rinsed mirror discis Fig. 4.-Test for determining the radius of curvature. A rhythmic action should he aimedat, dipped in water in order to walking round the post at the rate of oneprovideapartiallyreflecting Clear Class, step for each complete stroke ;after a fewsurface ;itis then stood up- Lamp. journeys round the post this action, includ-right against a wall or on a ing the little spin at the end of each stroke,shelf at one end of the twelve will become quite automatic, and the number feetspace mentioned earlier, of steps taken to complete the circuit of theas shown in Fig. 4. post will become constant. Standing a few feet away The " throw " of the stroke should ideallyfromthemirror,alighted be equal to the diameter of the tool ;care,candle is held in such a man- /1'74 28k -- however, should be taken not to exceed thisner as to cause an image of the Fig. 5.-The reflectiontest. 190 NEWNESPRACTICAL.MECHANICS March, 1948_

The shelf upon which the tin of 70 car-be followed by " smoothing' on a softer pitchthe pitch from being lostover the edge. borundum and the dish of water stood is tool. Immediately the pitch has set, but whilst it now cleared and the sheet of newspaper re- The 'advantages and disadvantages of hardisstill quite warm, the cardboard band is placed with a clean sheet ;this is to mini-and soft pitch tools might be summarised asremoved and the edge of the pitch roughly mise the risk of coarse gr:ts fouling the finerfollows:hard pitch polishes comparativelybevelled with a sharp knife lubricated with a grinding operations. rapidly and resists deformation due to handpaste of rouge and water. The tool on its base is replaced upon thepressure ; on the other hand the hard outer The mirror discis smeared with rouge post, and a tin of finer grit and a dish offacets tend to produce marked " ring " zonesand water and pressed hard on the warm clean water placed on the shelf. Grindingwken regular strokes are employed.Thesepitch at the same time moving it slowly back- is now continued with the finer grit. zones will be explained more fully in thewards and forwards and rotating it in a simi- . The coarsely ground surface will requirechapter devoted to figuring. lar manner to that employed in grinding. to be worked with the 90 carborundum until This is to form the surface of the pitch con- all the large grinding pits due to the 70 gritSoft Tools vex so that it is a perfect fit for the mirror. have been smoothed away ;a good check Soft tools possess the advantage of beingWhen all-overcontact has been obtained can be obtained by occasionally inspectingeasier to mould to the shape of the mirror,between the mirror and the pitch the mirror the surface with a magnifying glass. and also they do not produce edge zones.is removed and facets cut in the pitch. Successive grindings with the finer gradesThere are two very serious defects: the outer The pitch tool is shown in Fig. 6 and it of carborundum will produce a surface with facets are rapidly deformed by hand pressure,will be seen that itis divided into squares a fine, silky texture.Both discs and holderswhich causesthemirrortopolish morewhich form a pattern which isslightly off should be thoroughly washed when changingrapidly towards the centre, thus causing acentre ;if a square or the corner of a square grits, and the water and newspaper changed. central depressed zone which is exceedingly -is exactly in the centre of the disc the remain Scratches caused by the introduction of for-difficult tocorrect ;in addition, soft toolsing squares would form a pattern symmetric- eign grits at this stage can mean hours of polishveryally disposed about the centre, and such a back -breaking work to remove. slowly. tool would tend to produce polishing zones. Care should be taken to maintain intimate Pitch as ob- contact of the ground surfaces when using fained fromCutting the Facets thefinest grades of carborundum ;alittle the chemist is The facets are best cut with a sharp knife soap or glycerine added to the water, or usually t o olubricated with rouge and water ; a paraffin - good quality talcum powder added to the soft to use forsoaked rag should be kept handy for keeping carborundum powder willlessen the ten- polishing,al-the knife clear of adherent pitch.The chan- dency of the surfaces to adhere. though usefulnels .should be cut about one eighth to one The finer grades of powder will produce in this condi-quarter inch deep. an excellent surface with asoft, silky feel; tion for secur- When the faceting has been completed, this surface will not be transparent, of course ing the mirrorthe pitch tool should be allowed to stand -this condition can only be attained by toits handle.overnight with the mirror disc, 'coated with polishing. Polishingrouge, resting upon it ; this is to " iron out " A further simple test is available to prove pitchshouldthe edges of the facets, which would be raised the readiness of the surface for polishing. be capable ofwhen cutting the channels. The set-up for this test is depicted in Fig. 5. being frac- The mirror disc has its handle removed, A distinct white image of the filament should tured easily and the pitch scraped off and cleaned up with be seen on the surface of the mirror at the into smallparaffin. Greater control of the polishing 12 dez. angle indicated.If the image is red, fragmentsby and figuring operations is possible with the the surface is not yet ready for polishing, and Hardwood Or Class Tool light blowshandle removed, and the heat of the hands Base is equalised over the whole disc-an import- fine grinding must be continued until the withaham- reflected image is white. Fig. 6.-Plan and section of themer; a newlyant consideration to be borne in mind during An extra half hour spent at this stage inpitch tool used for polishing,fractured sur-the figuring operation. obtaining a perfect surface will save hours face should be A small quantity of rouge is placed upon of rouge polishing. the surface of the mirror and a little water just capable of taking a thumbprint, yet notadded ;the mixture, which should be of a soft enough to be depressed by the thumb.creamy consistency, is spread over the surface Polishing If the pitch obtained is too soft it can bewith the fingertip.The mirroristhen Polishing of the finely -ground surface ishardened by boiling, thus evaporating someplaced on the tool and polishing commenced. effected by means of a pitch tool chargedof its more volatile constituents.If too hard The actionissimilartothat used for with rouge.This tool can be made either byit can be softened by adding a little turpen-grinding, but the strokes are much shorter running melted pitch over the glass tool intine.. and should be slightly oval instead of straight situ, or by making a hardwood disc the same Sufficient of the prepared pitch to coverbackwards .and forwards ; the strokes should size as the mirror for use as a base for thethe glass tool or hardwood base to a depthbe constantly varied in length, to avoid tool pitch.The former method makes a goodof about a quarter of an inch is melted inedge zones.More weight is applied, using solid polishing tool, free from the riskofan old pan together with one ounce of bees-both hands,, and the disc rotated about zo deformation of the base ; there is, however, wax.It is then strained through muslin. deg. every two or three strokes. a danger of cracking an expensive glass disc If the glass tool is being used for a base, Polishing must be continued, occasionally by pouring on the pitch too hot.A hard-it should be dried and carefully warmed ;itrenewing the rouge, until the greyish ground wood based tool requires to have its pitchis then wiped over with turps. surfaceentirelydisappearsandbecomes surface re-formed before each spell of polish- The pitch is poured over the tool ; a bandTransparent.The mirror is then ready for ing ; that is to say, when it is left overnightof cardboard or stiff piper wrapped aroundtesting and figuring. the mirror is allowed to rest op it, thus pre-the disc and secured with string will prevent (To be continued) serving the surface contour and counteracting the effects of warpage. Polishing and Figuring For the purposes of polishing and figuring, two pitch tools should be used for optimum FOR ENGINEERS results-a hard pitch for polishing and pre- Screw Thread Tables, SI-, by post 513. Wire and Wire Gauges(VestPocket .. liminary figuring, and a softer pitch for final Book), 316, by post 319. smoothing. Refresher CourseinMathematics,816, The relative properties of these two types by post 91-. Screw Thread Manual, 61-, by post 616. ofpitchareofthegreatest importance. Theoretically,itmight appear possible to Gears and Gear Cutting, 61-, by post 616. Newnes' Engineer's Reference Book, 421-, polish and figure a good reflector simultan- by post 43I-. eously on one tool, but this would require an Workshop Calculations, Tables and impossiblyperfect combination ofcorrect Formulae, 61-, by post 616. Practical Mechanics' Handbook, 1216, by hand pressure, carefully calculated staggered Engineer's Manual, 10/6, by post J post 131-. strokes, and perfectly tempered pitch. The practical method is to obtain a pre- PlantEngineer'sPocketBook,61-,by liminark polish with a hard pitch tool, using post 616. staggered strokes in order to avoid as far as Published by possible tool edge zones ; then figuring on .a Newnes' Metric and Decimal Tables, 316, GEORGE NEWNES,LTD., TOWER HOUSE, hard tool with facets modified to alter the by post 319. SOUTHAMPTON STREET, STRAND, W.C.2 mirror surface from spheroid to paraboloid, and to correct polishing defects ; this would March, 19 48 NEWNES PRACTICAL MECHANICS 191 A CombinedPrintinA Box and SafelOht A Handy Appliance for Amateur Photographers

By L.C. MASON

THE pursuit of photography does notboard," or some similar ma- call for any large quantity of bulkyterial,such as was used for apparatus, but nevertheless an accu-blackout screens, should not mulation ofaccessories can soon createa be used. The sidesare storage problem. Whentwopiecesofmerely screwed or pinned to apparatus can conveniently be combined insmallsquarepastsinthe the one unit, thereby saving valuable space,corners, this being about the such a combination is worth considering. easiest joint to make.; It will The printing box here described also doesbe seen from the photograph duty as a safelight for enlarging.In additionthat a small door is provided to these two functions it has a number of inoneside,through which features not generally found in the normal asafelight oriicreen can be printing box. Ifthe reader does notatinserted. The cornerposts present do his own enlarging, the safelightend just below thisslot, and feature canlieused to provide a measurestrapsofwood, runalong of control when using the box for contactinside from corner to corner printing. to form runners to carry the safelight. The corner pieces Constructional Details extend up to the untler side As can be seen from the photograph,it of the runners.Similar run- consistsofalight plywood box carryingners are fitted above the safe - a conventional printing frame at the top andlight as well, to cut out any havinganelectric lamp mountedinthelight leaks past the edges of bottom.The box itselfis by no means athe safelight. Above the " cabinet maker's " job, being made of suchupper set of runners a further odd pieces of wood as were to hand. Theset of short corner pieces are Thecompletedprintingboxwiththesafelightpartli sides are of 3/16in. three-ply (Fig. t).Admit-fitted, which in turn end off inserted. tedly this isstill unobtainable in any quan-just below the edge of the box. tity, but small pieces-" offcuts "-up to 6in. The lid (Fig. z) which carries the printingpieceofwhitecardcoversthebottom wide are available if search is made for them. frame rests on the top of these corner pieces,and is held inplace bytheshade Indeed, thereisno reason why " hard -which should be of such a length as to bringring ofthe lamp -holder.This servesto the top of thelidflush withcover up the wiring and back of the switch Corner Posts Supporting Top the top of the sides.The lidand also to provide some gentle light reflec- Strips 5". t,"?'EXcludog AI/ Stray Light. inthis caseisa piece of thetion. The switch is of the " one -hole fixing " Runners '/2 x V? Supporting Safelight.,same three-ply from which thetype (Fig.3), such as most wireless junk riot For Insertion Or sideswere made, and has a boxes can provide.Check to see that itis Thickness Of ssfel,ght (Door' - rectangularholecutin it marked as suitable for mains voltages.The Detachable Top Omitted) slightlylarger thanthe aper-lead is merely a few feet of ordinary lighting tureintheprintingframe.flex led through a hole at any convenient The edgesofthisholearepoint near the bottom of the box. A hole in bevelledoffwith afileandthe side opposite to that carrying the door sandpaper and then blacked toand switch would probably be most suitable. prevent risk of reflections caus-Tie a knot in the flex just inside the box, ing a dark band near the edgeso that an accidental pull will be taken by of the paint.The lidis fixedthe side of the box and not by the connec- to the face of the printing frametions, which might part and blow the fuses. by small screws ; one into eachThe connections to the switch will probably side of the frame is sufficient. have to be soldered to small lugs on the Itisdesirable to make theback of the switch. Watch that these are not lidasndgfitinthe top ofbridged by a strand of flex or blob of solder. the box, so that although itis No dimensions have been given sofar. easily removed and replaced itas these depend on the size of printing frame does not slide about while thenormally used.However, in the box illus- clAmping springsarebeingtrated (Fig.t)the frame isthe 3%in. by manipulated. 21 -in.size and the box is6in. by Sin. by Itwillbe noticed thatthe 91 -in. high.The safelight is not a commer- door covering the safelight slotcially produced size, and consists of a sheet is double thickness.The innerof amber gelatine bound with passe-partout piece of wood just fits into thebetween two pieces of glass.It might be slot- soastoeliminatelight leaks from this point when the Edges Rounded Off And Backed Top,Cut For Snug Fit door isclosed. One hinge in /n Top Of Box the middle of the door is quite sufficient,asitisverylight. The moulding round the bot- tom edge serves no useful pur- pose, but an odd length was Cotner Posts Holding available, so was added for the Sides sake of appearance. White Card Reflector Hole For Switch Lamp -holders and Opening. The Same Held By Shade Ring Connections Size As Window" in Ordinary Printing Frame Printing Frame SCrewed On Top, Opening The lamp is mounted ina Fig. 1.-The printing box with one side removed to showbatten holder which is screwed Downwards interior construction. tothethree-plybottom. A 2.-Detachable top for the printing box. 192 NEWNES PRACTICAL MECHANICS March, 1948 worth while to make the box big enoughenable exposure times to be estimated nearnegative a 4o -watt bulb can be substituted, to take the standard Tin. by 5in. safelight. enough four times out offive. Doubtfulwhich will cut the exposure time by nearly casescaneasily be test -stripped with anhalf. Using the Printing Box opaque card in place of the screen.I find When used as a safelight the lidis com- When used asa simple printer the safe -that a 25 -watt pearl bulb is suitable for 99pletely removed. My darkroom is the bath- light is completely removed.If desired, itper cent. of negatives, which is also aboutroom, and as the walls are glazed with white can be replaced by a piece of ground glassright for a safelight.For an unusually densetilesfor some 5ft. upIfind thatifthe of the same size to give some diffusion of boxisinclined towards the light or to cut down its intensity when the wall thereisample printing from a thin negative.The ground 8ulgin'Type soft, reflected light avail - glass can also serve another purpose, and Switch. a b 1 e for comfortable thatisin the event ofitbeing necessary working. As thesafe - to screen or hold back part of the negative Lampho(der light glassis below the being printed.In this case it serves as the top edge of the box the support for a paper mask shaped to cover Connections lightis somewhat direc- the area to be held back.This islaid on Soldered. tional and can thus be theglassand, of course, blocks out the easilykeptaway from light where required.Part of the exposure such undesirable any spot, only may be given, using such a mask, and as the enlarger baseboard. then glass and mask removed to give the Finishisa matter of remainder,inthe knowledge thatneither choice ;a coat of varnish lamp, negative nor paper has moved since might be useful, as in the the start of the exposure. Safety Knot. event of the box getting Itwill be found that with such factors (lust Inside Box) splashedthevarnished as light strength and lamp -to -negative dis- surfaceiseasilywiped tance constant, verylittleexperiencewill Fig. 3.-Details of plug, lamp -holder, switch, and connecting lead.clean and dry.

227o b.h.p. in 1947-an increase of over 71 per cent. in ten years. Aviation Notes The Hercules 634, as fitted to the Viking, has, with standard 100/130 grade fuel, a take- HerculesEnginesforSouth Africanforitself in th's part of the world. Theoff power of 1690 b.h.p. ; a maximum emer- Airways crews have complete confidence in the enginegency power of 1795b.h.p. ;a maximum NEWS that South African Airways haveand waste no timeintellingtheirrival continuous power of 155o b.h.p. and a maxi- put the first six of their fleet of eight brothers, who fly Skymasters ard Lodestars,mum continuous power of 133o b.h.p.on lean Vickers' Vikingsintoservicerevealsthat all about its finer points and high perform- mixture. the " Bristol " Hercules engine has estab- ance. . ." lished yet another sphere of operations in its The Hercules, which enjoys the distinctionBritain's New "Flying Wing." already impressive rezoed of activities. ofhaving powered nearlythirty different Entailing an approximate monthly mile- types of military THE Armstrong Whitworth jet-propelled age of 65,000 miles, South African Airways itsinception, achieved a continuity of in- " Flying Wing " was recently4demon- are operating three return services per weekcrease in maximum power output unequalled strated on the ground and in the air at Bates= between Johannesburg and Cape Town viaby any other type of aero engine. Fromwell Aerodrome bytestpilotSquadron Bloemfontein. 1325 b.h.p. in 0937, the power has risen toLeader Eric Franklin, D.F.C., A.F.C.Pow - Enthusiastic reportsof the performance of the engines in these aircraft have already been received by the Bristol Aeroplane Com- pany. One aircraft is due for check after a very successful too hours' flying. During most of that time it has been used for train- ing crews, development flightsround the Union, and has operated inthe Rhodesia - South African service. Mr.J.A. Danes," Bristol "engineer stationed at Transvaal, reports that " the Her- cules engine is establishing a very good name

Two views of the Armstrong Whitworth " Flying Wing."

ered by two Rolls-Royce "Nene " engines, and produced at a cost of nearly £200,000, theFlyingWingrepresentsthemost advanced type of research machine in the world. With a wing span of 90 feet the machine can climb at 4,80oft. per minute, and cruise at36,000ft. for 1,500 miles, at 33o m.p.h. This all -metal tailless aircraft is of revolu- tionary design, and is the prototype of the airliner of the future.Fins and rudders are at the wing tips. March, 1948 NEWNES PRACTICAL MECHANICS 193 Electric Water Heating Practice -2 Calculating OptimumLoading Tank Capacities Various Types of Water Heaters Heat and Electricity B GAT BURDETT A M I IA Using the figures 3 kW., 4 hours, 8o per BRITISH Thermal Unit (B.Th.U.) is the (Continued from page 170, February issue) cent. efficiency, 126 deg. rise in temperature, heat required to raise'lb. of water we get : throughtdeg. F.This is equal toa given loading, the following formula is used : ' 4' So 0.293 watt hours, which is alittle under Temp. rise in deg. F. 3 3415 - 25gallons. to;;too 126 totoo oft watt hour. 3415 loading in kW. x efficiency Overall efficiency of heater is obtained thus : watt: 3.4153.415 B.th.U. per hour. Assuming a temperature rise of 126 deg. F., kilowatt hour (kWh) or 1 unit is equal to Temp. rise in deg. F.galls. x to x too 3,415 B.Th.U.s. 3415 -loading in kW. x time in hours. Assuming temperature of the incoming If temperature rise is too deg. F., capacity cold water is 54 deg. F., and it is required to 20 gallons of water, loading is 3 kW. and time raise t gallon to 18o deg. F. or through 126 taken21!hours : deg. F. at too per cent. efficiency, electricity too X 20 X I0too Efficiency - 78 per cent. consumed would be 0.37 kWh, or 0.37 x 20 - 3415 x 3 x 2.5 7.4 kWh for 20 gallons. These figures are representative of normal At So per cent.efficiency, consumption operating conditions and therefore an ade- would be 0.46 kWh and 4.6 kW. fort and to quately heat -insulated tank has an approxi- gallonsrespectively. To ascertain the electricity consumed for any set of conditions, the formula used is : Anti-Drip Units consumed = Syphon Galls. of water x temp.rise in deg. F. x sotoo 3415 X efficiency per cent. With 20 gallons of water, 126 deg.1-. temperature rise and an efficiency of So per cent., we get 20 X 126 X I0I00=9.2, or 9 units approx. 3415:8o8o To estimate the loading of an immersion heater, in kW., to heat water in a given time, the formula used is: Temp. rise deg. F. x galls. capacity x so x too 3415 / hours X efficiency per cent. Assuming temperature rise is 126 deg. F., Hot Water tank capacity 20 gallons, heater efficiency 8o Outlets per cent., and the given time or recovery period is to be 4 hours, we get : 20 X 126 X I0 X I00=2.3. kW. 3415 x 4 x 8o (a) (b) This 2.3 kW. switched on for 4 hoursFig. 9.-Pyrex container removed from outer consumes 9.2 kWh. casing shows the operation of the displacementFig.Ir.-Anti-dripdeviceondisplacement As no 2.3 kW. heater is made the choicetype water heater.The mushroom head of thetype water heater. Upon the closing of the lies between 2 kW. and 3 kW.If hand anti -drip device can be clearly seen. control valve CV, waterlevelisat" A." controlled, the larger size should be adopted.capacity of tank 25 gallons, immersion heaterWater still runs up outlet by syphonic action In fact, manufacturers install a 2 kW. heaterof 3.o kW. loading and an overall efficiencyand thelevelisreducedto" B."Water, in self-containedlagged automatic storageof So per cent. upon being heated again, can expand to " A '' heaters of zo gallon capacity. Time taken in hours - before dripping occurs, but this rarely happens. '26 x 25 x to ,: too Where it is necessary to ascertain the time 4 hours approx. mate efficiency of 90 to 95 per cent. and the it would take to heat a quantity of water with 3415 x 3 x 8o approximate efficiency of a non -insulated tank Sheet Steel Ventilator If the temperature rise is known,So to 85 per cent. Outer Casing the heater loading, overall efficiency G. Where only rough cal- 7 Anti- syphonic and the time taken to raise theculations are needed the inlet Pipe water to that temperature, gallonsfollowing will give heated can be ascertained with theapproximate requirements Anti -Drip formula : within a reasonable degree Device .,/ / mersion kW. x 3415 x hours x efficiency perof accuracy. Heater cent. Temp. rise in deg. F.totoo Thermostat Cold Tap To Water Heater Fixing Tnned-Copper Cold Inlet Brackets Welded Container Copper Pipe Granulaeed Iron Pipe Cork Lagging or Rubber Hose -case Ring Rubber Casket Base Plate

Drain Plug T Piece

Bottom Cover Inlet Tap Plate

Swan -Neck Outlet Pipe

Fig. io.-A displacement type, singlepoint,i4 gallon water heater, ani nictlol of con-tecting it to cold water mains.Compression fittings of the Kontite type are used, which require no plumbing or soldering.Alternatively, a piece of rubber hose will mak- 2 satisfactory connection.

a 194 NEWNES PRACTICAL MECHANICS March, 1948 lectricity Consumption made of sheet copper, with lapped or weldedstatically controlled and are well lagged, theie One unit of electricity (kWh) will raise : jointsand tinnedinside.Smallestsizes,is little advantage gained in switching them 2 gallons of water at average cold mainsif gallons, sometimeshaveheat -resistingoff except when not in use for long periods temperature (52 deg.F.) to boiling pointglass containers of the Pyrex type (Fig. 9),of about four days or more. Therefore, (212 deg. F.) ;3 gallons to 15o deg. F. andand are suitable for culinary purposes whererecovery, or the time taken to heat up the gallons to too deg. F. the water supply is taken direct from the mains.total contents is not very important provided Monel, a special non -corroding alloy, is alsothe correct size of heater is installed. Approximate Capacity of Tank used for containers. Approximatecapacity,ingallons,of issurrounded by heat -Non -pressure Type of Water Heater rectangularandcylindricaltankcanbe The container insulating material, such as granulated cork, This type, also termed displacement water found from the formula: : and covered by an outer metal case, stoveheater because the supply of hot water is Rectangular : enamelled white. With the exception ofcontrolled by a tap in the cold water inlet, is Length x breadth >, height=gallons special models, heatersarecylindricalinmade in the smaller sizes only.When the 280 shape, to give the lowest surface area for ainlet tap is opened the cold water displaces All dimensions in inches.. given capacity, and, therefore, lower heatthe hot by an overflow leading to an open

t8in. x t8in. x zoin. -23 gallonsapprox.losses.They are also designed to withstandspout, Fig. to. 28o a water pressure of 5o1b. per sq. inch, which The threemostpopulardisplacement Cylindrical : is equivalent to a tt5ft. head of water, rarelytypes areif,3 and 5gallon sizes ;the met, of course, in domestic premises. smallest being most extensively used for Diameter x diameter x height-.gallons 35o Inlet pipe is in the base of the containerdomestic purposes and ideal for fixing over 15in. x 15in. x 36in and has a baffle, usually of mushroom shape,the kitchen sink, over the wash basin, or any =23 gallons approx. position where small quantities of hot water 35o fitted over the open end to prevent incoming Water is normally stored incold water mixing with the hot, and enablesare required at frequent intervals. the tank at a higher tempera-from 75 to 85 per cent of the heater contents One outlet only can be supplied from the to be drawn off without any noticeable falldisplacement type,itbeing essential that ture than at which itis used. the outlet is always open or pressure would By mixing with cold water, thein temperature. build up in the heater and damage would rightquantityattheright The outlet pipe is also at the bottom of temperature is obtained. Forthe heater, though in some heaters, as willresult. be seen later, a second outlet is provided at Installation is simple.Existing cold tap the top.This arrangement of two outletsis removed and a tee -piece inserted and the (a) simplifiesplumbingtap replaced. A few feet of piping is then where outlet taps are toinstalled between heater and tee -piece and be fed above and belowno other plumbing is necessary. the heater. Special fittings may also be used which Heating element andconsist of two compression pieces.One, an thermostat are mountedelbow, is fixed near the inlet, and the other, on an apparatusplatea tee, in the cold water supply.A short Open Bib mountedverticallyonpiece of copper piping is installed and the Tap OPettthe bottom of the waterunionsaretightened(Fig.to).These, Bib container in the smallestknown as the Kontite fittings, require no /The heaters, which are fixedplumbing or soldering. Alternatively, a on the wall; and horizon-piece of rubber hose pipe may be used, but tally in side of the largethe copper pipe is more satisfactory. heaters which, owing to Average use of hot water from a tf gallon their weight when fullheater in the kitchen is 6 gallons per day at of water, stand on the18o deg. F., which gives the user to gallons Cold Feed floor. of really hot water for a daily consumption of 2.5 kWh. or units per day.This heater (c)Loadings needneverbeswitchedoff,andthe ( b) Electrical loadings ofstandby losses are only 4 units per week.In Fig. 12.-Open bib tap (a) which can be fitted to open outlet of displace-self-contained waterview of the convenience of constant hot ment type water heater.This is shown in a wash basin (b), while in heaters are standardisedwater, itisworthwhile, therefore, leaving (c) the tap has been modified to provide ease of plumbing. and have been fixed as athe water heater constantly in circuit for result of long experiencesuch a small weekly, loss. instance, temperature of water for washingby manufacturers and supply authorities, and Displacement, or non -pressure type water up should not be more than scalding tem-range from 5oo watts or the If gallon and 6.oheaters, are made in capacities up to3o perature, which is 120 dtg. F. and for a bathkW. or more for the too gallon size.Thesegallons.The 12 and 15 gallon heaters are the average temperature is105 deg.Thegive a recuperation, or recovery periodofsuitable where two baths are not taken in amount of water required for a medium-sizedabout four hours (except for the smallest sizes,quick succession, and the 20 and 3o gallon bath is about 22 gallons ; to gallons at 18o deg.where itisless), but as theyare thermo-heaters for larger premises or where two mixed with 12 gallons at 5o deg. F. consecutive baths are frequently required. The formula for ascertaining the resultant Loose Cover Cold Water temperature is: .1 Resultant temperature= Mains Gals. hot x temp. hot + galls. cold x temp. cold Cold Water Totalgallons Air Lagged Overflow Main to x 180°-1-12 x so°-109° F. Expansion Adjustable 22 Pipe Inlet Valve Assuming thatthetemperatureof the, hot water is160 deg.F., and this figure should not be exceeded in hard water districts or scale will form and the elements' and heater'seffectivestorage reduced, Heater; 160 X IO-F 12 X 50 too°F.resultant temp. 22 Thermostat Where in the former case two good baths can be obtained in quick succession from a 2o -gallon water heater, in the latter less cold water must be used to obtain the required Baffle temperature. Alternatively,somelittle time must elapse between the two baths. In practice, where the loading of the heater is 3 kW. or higher, sufficient recovery is made 11 Hot Ware. 11\ by the time the first bath has been taken. - r In effect, therefore, two consecutive baths Cold Water Outlets are possible from a 20 -gallon water heater. Fig. 13. --Cistern type water heater, which is a self-contained water heating system. Usually Self-contained Water Heaters the cold water mains may be connected direct to inlet.Closed (tap) outlets may be run from These consist of water containers, usually the outlet and therefore minimum plumbing is required. At arch, 1948 NEWNES PRACTICAL MECHANICS 195

Feed hot water system will therefore depend upon 6----...--Etpansfon Pipe the height of the cold water feed cistern Outlet ToBath Etc. above the storage heater, as in the normal solidfuelsystem. The cold water inlet Outer Container is situated at the base of the heater, and the hot water outlet at the top, to which is con- loner Container Overflow 71" Bore 4 Bore nected the system expansion pipe from which the hot water outlets arc run (Fig. 14).Any C.'ork Lagging c Bath number of hot water outlets may be run from a` the system.Outlets can also be taken from Healers - J below this heater, as indicated. Pressure -type water heaters may be used Thermostat InietP4ce Basin either as the sole source of hot water supply, Bore, or in conjunction with the solid fuel system /n/et Baffle (Fig. 15). When the latter method is adopted, -1711- r: flid k':.1 _St not only does it act as a booster heater when Cold Water thesolidfuelboilerisinoperation, but /n/et Outlet Pipe Bore serves as additional storage capacity, which Water greatly adds to the utility of the existing Outlet To Hearer system. z Bore H lVarious Points Hot water outlets may be situated above ticks Etc 3 nk Cold or below the heater but not, of course, above Feed thecoldwatercistern,whichisusually Drain Cock---- 'n/et JI situated in the loft. The expansion pipe, which extends to a Fig. r4.-Pressure type water heater for wall fixing:Outlets may be taken either fro n the top position above the cold water storage tank, or bottom.This heater must be fed front a ball -valve type of cold water cistern.Outlets arc of the closed (tap) type.Floor standing models operate similarly, but the immersion heater is installed horizontally to allow for inspection.Piping arrangemenre are shown in the diagram on the right. Although only one outlet is allowed to be Advantage of method (b) taken from displacement heaters, two pointsis that all the hot water can such as bath and wash -basin can be servedbe drawn off without drop by one heater by fixing it on the wall between'in temperature since incom- the bath and basin and arranging the swiveling cold water. isso slow spout accordingly. thatitdoes not mix and t cause cooling. Thisis Anti -drip Arrangement achieved by the incorpora- Water expands approximately 4 per cent.tionofarestrictedcold in volume when heated through a temperaturewater feed between ball - Oen rise of 15o deg., i.e., from 4o deg. F. -I90valve cistern and hot water t deg. F., which is approximately the rise incontainer.This adjustable temperature in the normal installation. water feed valve is shown ra Ar;the displacement type 'waterheaterin Fig. 13. has an open outlet, dripping, due to expansion of the water on heating, would occur. Self- Where water supply auth- containedstorageheaters,therefore,areoritiesdonot allow this fittedwith an anti -drip device, the mosttype of water heater to be 'common being in the form of a syphonicconnected direct to the main trap formed at the top end of the outletsupply,itshould be con- pipe.When the cold water inlet valve isnected to a downward feed from thc house cistern. 1111111. shut off, water continues to rim for a few fllvi seconds as the level of water in the container In the heater illustrated drops slightly to allow for this expansion.in Fig.13it will be seen Fg. f5.-Utilising a presst re type self-contained zvater heater When the tap is turned on again there is athat the immersion heater itconjunction with a solid fuel " boiler " system.Since the delay of a few seconds before the hot waterand thermostat are enclosed electric heater is fed front the outlet of the hot water storage flows.The user soon becomes used to thisinacylinder. This is tank, when the fire is lighted the electric heater may he used as a characteristic, and operates the tap accordinglyalways full of water and is a booster heater.Total storageistherefore ino cased. (Fig.i 1). precaution against burning Where itis not convenient to install theout the heater when the water container ismust always have an open end or undue water heater over the sink or bath, a lengthdrained, either through failure of water sup-pressure will build up in the water container of pipe may be run to the tap position and,plies or when the constant temperature variableas the volume of the water expands.Also, as it must have an open outlet, this tap can bevolume system is used.The thermostat thenthis pipe should rise vertically without bends replaced by an open bib tap (Fig. 12). operates when the small quantity of water .to provide an outlet with minimum resistance. reaches the pre -determined temperature. From thispipethehorizontalhot water Cistern -type Water Heaters service pipes are run.Therefore, the size of Thesearecomplete,compactelectricPressure -type Water Heaters the expansion pipe should be large enough water heating systemsinthemselves, and This type of storage water heater is funda-to provide maximum flow to all positions. comprise : storage water container,mentally the same as the hot water storage immersion heater and thermostat and balltank in the normal domestic hot water system (To be continued.) valve system contained in one outer casing.after conversion to electric, but itis factory Provision is made for cold water inlet andproduced. Capacitiesrangefromthree overflow, and hot water outlet (Fig.13). gallons with an electrical loading of i kW. Standardcapacities(hotwaterstorage)up to too gallons with a loading of 6 kW. range from 5 gallons up to too gallons withor more.Special models are also rhade for MASTERING MORSE standard loadings.These can be connectedindustrial and commercial application with direct to the cold water mains supply, andhigher loadings and capacities.Smaller sizes, By the Editor of any number of hot water outlet points may3-3o gallons, are arranged for wall mountirkg, PRACTICALMECHANICS be supplied, but since they ate gravity fed,and above this capacity are floor standing. no outlet must be situated at a higher level Pressure -type water heaters are made and than the storage tank: designed to operate in a similar manner to 3rd EDITION the displacement types but, instead of having Cistern -type water heaters operate on either This handbook, written with special regard for service of two forms,(a)constant volume andan open outlet, the system operates under requirements, will unable even the beginner rapidly variable temperature where the cold water isa pressure, with the control points on the tobecameproficient insendingandreceiving. hot water outlets instead of the cold water drawn off and the storage container is always Of all Booksellers, or by pest 1/2 from full of water, and (b) the constant temperatureinlets. I /- GEORGE NEWNES, LTD, (Book Dept.), If. variable volume system, where hot water Heaters of this type should not be con- net Tow ;r House, Southampton Street, net can be drawn off at a greater rate than thenected to the mains water supply, but from London,W.C.2 cold water enters the chamber. a low pressure tank supply.Pressure of the 196 NEWNES PRACTICAL MECHANICS March, 1948 The Elements of Mechanics and Mechanisms -5 ByF. J. CAMM (All Rights Reserved) Opposing Forces-Third Law of Motion WE have dealt with the case of a bodyweight will be found necessary to restorethe table and placed it on the floor.Muscular moving with a certain force which hasequilibrium when the iron is brought belowforce is used in this case, but it would be produced a given velocityin onethe scale pan containing the magnet. ineffectiveunlessitcould overcomethe direction, while anotheracts onitfrom In the example of a person pressing againstresistance of the weight, due to gravity.In another direction.The rule for finding thethe wall, he may exert such great pressureliftingtheweightwehaveperformed resultantof velocities. actinginoppoSitethat he himself isforced back.To breakmechanical work. directions is :Subtract the smaller velocitya piece of string two persons could hold When the weight has been placed on the from the greater.The motion will, of course,the ends and pull in opposite directions.table it might at first sight appear as though take place in the direction of the greaterExactly the same results would be obtainedthe table were doing work in keeping it in with the velocity of the difference betweenif one end of the string were tied to a hookplace against the force of gravity.Since, how- the two. in the wall. ever, thereis no motion and the weight Assume that two balls of iron of the sameAnother Example retains its position, no work is being done ; mass are rolling towards each other, one When a ball is held in the hand the forcea man who stands still with a weight* in his with a velocity of soft. a second, and theof gravity tendsto drawitdownwards.arms is doing no work.If a rope is attached other with a velocity of 4oft. a second.WhenEqually, the ball tends to pull the earthto the weight and it is dragged along the floor they meet the velocity of the first will negativeupwards but, of course, to an immeasurablyor the surface of the table a certain amount of soft. per second of the velocity of the other -fine extent. When the ball is set free it tendsresistance will be felt.This is caused not by ball, which will be left with a velocity ofto draw the earth upwards just as muchtheattraction of gravity, because thatis Soft.persecond.Thiswillbe dividedas the force of gravity tends to pull the ballbalanced by the reaction of the table or the equally between the two balls, which will rolldownwards. floor, but by the friction of the weight uppn away each with a velocity of ssft. per second, Now how is this motion measured ?Itits supporting surfaces.If the weight has a in the direction in whicli the faster ball wasis measured by the momentum, that is to say,polished surface the resistance will be less, moving when they met. the quantity of motion of the two bodies.and if the top of the table, for example, is Bodies thrown upwards provide a furtherWhen they meet, their momenta will be equal.covered with glass it will be even less. We instance of a force acting on a body in motionBut as the mass of the earth greatly exceedsshould thus be doing less work, because there in a direction contrary to that in which thethe mass of the ball, the velocity of the earthwould be less resistance. body is moving. will be proportionally less than the velocity If the weight and the tabletop were We can cause a ball to rise in the air byof the ball.Thus, if the ball had beenperfectly smooth there would be no resistance muscular force, but whilst it is rising the forcefalling for s second at the moment it meetsat all, and however much we move the weight of gravity is acting on it, tending to pull itthe earth, it will have a velocity of 32 ft. perabout we should do no work, since there would down.The force of gravity isa constant,second.The upward velocity of the earth,be no resistance to overcome.When a cart never -ceasing force, and it continues to acthowever, because of its greater mass, will beis drawn along the road only friction has to on the ball all the time it is rising.That istoo small to measure. be overcome, friction in this case being the the reason why the ball attains a tertain From this it is concluded that one bodysum of the resistance in the hubs of the wheel altitude and then returns to earth. cannot attract another without itself beingand the tractive resistance of the tyres in All our movements on the earth illustrateattracted by that other body.Again, wecontact with the road. the second law of motion because in additioncannot have action without reaction, and they When a hill is encountered, the horse has, to the movement of our bodies caused by ourare always equal and opposite. in addition, the force of gravity to overcome, own muscular efforts we also partake of the The attraction of the earth and the moonand heistherefore performing agreater motion of the earth.When we jump weis mutual ;they both attract one another.amount of work. fall again on the same spot of ground. But as the earth is larger and heavier than Now when we have to measure work we The Third Law of Motion the moon, the motion of the moon is affectedmust first decide upon a unit as with measure- far more than the motion of the earth, andments of length, area, capacity and weight. Newton's Third Law of Motion states thatbecause of the earth's greater mass the moonTo fix upon a measure of work it is necessary " to every -action there is an equal and contrary to consider the motion of the body on which reaction," in other words action and reactionis caused to circle round the earth.The are equal and opposite. A spring balancereacting force of the moon draws towards itthe work is performed and the 'resistance that provides an example of it. the waters of the ocean, and produces thehas to be overcome in order to remove it. If we place aphenomenon known as the tides. Motion can be defined by recording how weight on the hook of the balance, gravity When a gun is fired there is the actionmany feet the body has moved, and resistance acting on the weight causes the spring to.of the powder enforcing the bullet or shellis best expressed by comparing it with the stretch and the weight to move downwards. resistance to be overcome when a body is When the weight has moved a certain distancefrom the muzzle, and there is also an equal and contrary reaction in the recoil or ricochetraised from the earth.This resistance, is it comes to rest,. The opposing action ofof the gun against the shoulder of the personusually expressed in pounds, and it is due to the spring against the force of gravityis firing the gun, or of the gun against itsthe force of gravity.Because this force is responsible for this, andthetwo forces are constant and always in action, it is the best said to be in equilibrium.It is the reactionmountings.If the mass of the gun is 500 of the spring against the action of gravitytimes that' of the bullet, then the velocitymeans of measuring work. which causes the weight to be in equilibrium.with which the gun is forced back will onlyUnit of Work This law holds good in all cases.If yoube one-fivehundredth of that imparted to the The unit or standard of work usually push against the wall with a pressure of so lbs.bullet. adopted is that which is done in raising a weight the wall pushes back with a pressure of to lbs. When a rocket is fired it obtains its motionof r lb. through a vertical height of x ft. If a piece of iron is suspended on a stringfrom the reaction of the force with which This unit is known as the foot pound. and a magnet is brought near to it, the ironthe exploding gas escapes.It does not obtain If a weight of so lb. be raised sft., to times will be attracted towards the magnet.Ifit, as so often has been thought, by the gasas much work will be done as when s lb. was the magnet is suspended the iron will bepushing against the air.A rocket is moreraised ift. found also to attract it.Thus the actionefficient in a vacuum when there is no air to Again, if a weight of 2 lb. be raised 4ft. of the magnet on the iron and the reactionpush against. it will take twice as much power as is required of the iron on the magnet are equal.IfWork to raise 2 lb. 2ft.Thus to raise a weight of the iron be placed in the pan of a pair of Work is defined as the production of motionsorb. 1ft. we shall require to lb. of force. scales and balanced by a i lb. weight it willagainst resistance.If a so lb. weight is lifted This may be reduced to a rule : The amount require perhaps a second pound weight tofrom the floor on to a table, work has beenof work required to be done is equal to the balance it when the magnet is brought under-done.Because of its inertia the weight wouldweight in pounds of the body multiplied by neath the scale pan containing the iron. remain on the floor until some force acts uponthe vertical distance in feet through which If the position of the magnet and the piece.it, as we have seen earlier.Similarly, workit is raised. of iron is transposed, exactly the same extrawould be done if we removed the weight from (To be continued.) March, 1948 NEWNES PRACTICAL MECHANICS 197 Nitrogen

Silver Ballistics in Foil Nuclear Physics 11 Fluorescent Screen Zinc Sulphide Notes on This Important Science Nitrogen Fig. "-Rutherford's transmutation By FRANK W. COUSINS, Grad.I.E.E. of nitrogen. IT was the dream of Hermes TrismegistusThe nitrogen atom was bombarded by fast-that the lithium nucleus (mass 7) absorbed a and his followers, the alchemists, thatmoving helium nuclei (alpha particles) givingproton (mass I) to form a nucleus (mass 8) they should discover the philosopher'sunstable fluorine which gave an isotope ofwhich disintegrated to form two helium nuclei stone, reputed to turn or effect the trans-oxygen (017) and hydrogen. The experiment(mass 4 each).The equation being : mutation of base metal into gold, and to findconsisted of placing radium in a container The cult was very strongwith nitrogen, and arranging for the end of LiIH-4.84Be--0.411e energy the elixir of life. 3 . 2 2 between the 12th and 17th century, and manythe container to be covered by a foil sheet andIn 1934, at the University of Rome, Prof. were the great names coupled with its teach-a zinc -sulphide screen ;scintillations immedi-Fermi proceeded to bombard most of the ings and researches.To -day, the elixir ofatelyappeared. This suggested that theknown elements in the periodic table with life would appear to be most remote, butalpha particles from the radium had expelledneutron projectiles.He found that in many HermesTrismegistushasbeenabsolveda proton from the nitrogen nucleus, and thiscasestheneutron was captured, and an before his progeny. would mean theautomaticformationofelectron emitted from the unstable nucleus ; another element (see Fig. t). this raised the positive charge of the nucleus Rutherford and Chadwick showedthat 3E1. other lightelements were transformed byby one and thus transmuted the" old " KI nucleus to the nucleus of the next element SI alphaparticlecapture,anditwas soonin the periodic table. realised that to carry investigations to a more Hahn, by chemical methods, investigated X/ successful stage powerful sources of atomictheunsatisfactoryconclusionsof Fermi's projectiles were desirable, and pioneer workassault upon the uranium nucleus, and he K2 upon atomic ballistics was begun, to assail the 3P S2 , was able to show that the uranium nucleus armour of the nucleus. upon the absorption of a neutron underwent X2 In1932,atthe Cavendish Laboratory,a splitting into two lighter elements, of nearly S,13 Cockcroft and Walton performed thefirstequalmass,bariumandkrypton,the K3 transmutation, using a machine or devicephenomenon of nuclear fission. Great energy S3V whichgeneratedtheballisticforcesandis produced when fission occurs since the produced a high energy particle capable ofproducts of the fission possess a total mass entering the nucleus.Their apparatus con-less -than theoriginal nucleusinvaded by -4-, sisted of a voltage multiplying rectifiertothe neutron andthelittlepieceoflost Fig. 2.-CockcroftandWalton'svoltageobtain high voltage at a constant potential.mass,f m,is transformed into energyin multiplying circuit. Thesimplifiedcircuitappearedintheiraccordance with Einsteiri's classic equation : report(1) ;it was an ingenious adaptation ofE c2 where c is the velocity of light. The Pioneers the impulse generator overcoming the main With these facts before the scientific world In the late19th century Becquerel dis- itbecameincreasinglyclearthatitwas covered radio -activity, in that certain uranium Accelerating rube important to manufacture devices capable of salts were found to produce energy spon- generating projectilesfor nuclear research, taneously and apparently continuously. so thatthe nuclear physicist could direct nuclearbulletsatanychosentargetto Professor Pierre Curie and Madame Marie investigate the possible nuclear reaction. Curie showed that this was due to radium, a Proton Bean, The particles used in this nuclear ballistic substance which they managed toisolate. art usually fall under one of the following Further cleverresearches showed that radium headings : was one of a series of elements from uranium to lead, which change spontaneously over a Lithium Forget (a) alpha particles .. helium nuclei. definite time period from one to the other ; (b) Beta rays ..electrons (fast). the alchemists had not been so far wide of the (c) protons .. hydrogen nuclei. truth when they hoped for the philosopher's (d) deuterons .. heavy hydrogen stone. Fig. 3.-Diagram illustrating the bombardment nuclei. That any real detailed light was thrown of a lithium target. (e) neutron .. electron and proton upon the sub -microscopic subject of radio- closely bound. No activity was owing to the persistent genius anddrawbacks of that type of circuit,viz.,a . electric charge. the classic researches of Ernest Rutherford,momentary discharge, and providing an un- (a), (b), (c) and (d) may be accelerated by later Lord Rutherford of Nelson, who, work-interrupted current flow (Fig. 21.The threea cyclotron orelectrical machines termed ing at the Cavendish Laboratory from 1919,parallel condensers K K2 and K each ofgenerically magnetic induction accelerators, showed that the energy -changes associatedthe same capacity, are connected in series tothe betatron, or synchrotron, or by an electro- with radio -activity were of a high order inthe supply E. A further pair of condensers,static generator such as the Van de Graaff comparison with the normal energy associatedX, and X,,are connected to K1, K Kgenerator, (e) the neutron having no electric withchemicalchanges. Rutherford andas shown. The switches (dotted), SS2andcharge is produced as a secondary projectile Niels Bohr had expounded their conception are originally connected, and these connect from the bombardment of a suitable element ; of the model of the atom, showing that itX, and X to K,, and K, ;when comprised a centre sun or nucleus of positivethe switchesare moved to the Accelerating Gaps charge surrounded by electronic shells, theupper positions S' S'2, Sts )(2 /on electrons of which were constrained to moveshares., itscharge with K, and Source rarget in fixed orbits.It followed that whereasboth will be charged to E',, the normal chemical changes were made in thenext reversal and K, and X, will orbital electron zone of the atom, the radio-be connected and take up potential active energy changes were owing to changesE', while X, will be recharged to in the structure of the nucleus. potential E. Charge will gradually be transferred to all condensers until in tht Transmutation absence of loss a potential 3E will develop F Oscillator In1919 Rutherford and hiscolleaguesacross the condensers K1, K,, K, in series. performed an actual transmutation of the Cockcroft and Walton were able to draw of Fig. 4.-General arrange - element nitrogen, obtaining an isotope continuous currentatvoltagesas high as wentofalinear oxygen. The equation being : 700,000,thisbeingutilisedtoaccelerate accelerator. 14N i_,_).14 18F 170IH protons (hydrogen ions) for the bombardment 7 2 9 8 ' of a lithium target (Fig. 3).It was found

ffi 198 NEWNES PRACTICAL MECHANICS March, 1948 for example, they may be given off whenincrease in 'energy does not give, entirely, an Extract I beryllium is bombarded with alpha particles.increase in velocity, this phenomenon causes Extract' We will now consider these machines inthe particle in the cyclotron to fall out of Inject Inject detail in that they are the essential tools ofstep with the high frequency voltage across the nuclear physics laboratories from whichthe D -shaped electrodes and sets a limitation future developments will come. to the usefulness of the device.For similar reasons coupled with the low mass of the The Cyclotron electron, the cyclotron has not been used to at a produce high energy electrons (beta rays). The cyclotron was invented by Dr. E. 0. Time Lawrence (z), and for his,work in this connec-The Betatron Original Acceleration Period tion he was awarded the Nobel prize.The The betatron was firstdescribed by a a2 Acceleration Period When Zero principle of the cyclotron came to LawrencephysicistofSiemens-SchucertwerkeAk- Line /s Lowered. after his great experience with linear accelera-tiengesellschaft(3) of Berlin-Siemensstadt, inFig.7.-Westendorp'simprovementinthe tors, wherein the particles were accelerated1937, but it was developed and perfected by acceleration period. acrosso number of gaps between a number of D. W. Kerst (4,5,6) of the University of metal tubes inseries,the alternate tubesIllinois.It possesses a modus operandi quite It is of interest to record that the General being connected to the opposite poles of andistinct from that of the devices describedElectric Company of America have made a oscillatory circuit (Fig. 4). so far.The fundamental components arebetatron which is capable of generating to° The cyclotron overcame thedifficulties electron volts ;difficulties are experienced, experiencedwithlinearacceleratorsby however, at these very high energies; since causing the particles to move in a substantially theelectron of relatively low mass soon archimedian spiral, and it introduced a new approaches a velocity close to the velocity of principle into the nuclear ballistic art, in that light (c) since this sets a limit to its movement the acceleration force was providedin a any additional energy intake results in air series of pushes applied to the particle as it increase in the mass of the electron itself ; passed a specially constructed gap. The at even greater energy levels radiation of the fundamental Principleisbased upon the energy appears in the form of electro-magnetic phenornelioathat a charged particle moving wave% and the dissipation of energy in this in a planerpendiculare 'P to a uniform magnetic Class Doughnut form may become substantially equal to the field describes a circular orbit at a constant Pe moved From acquisition of energy. Magnet angular velocity regardless of its speed. In its simplest form the cyclotron consists The Synchrotron of two D -shaped electrodes (Fig. 5), having a The synchrotron isa modified betatron, shallow box -like form, within an evacuated the essential modification being arranged to chamber situate between the poles of an overcome the drawbacks referred to in the electromagnet of great power. The D -shaped preceding chapter. electrodes are connected to a high frequency The modification consists of the inclusion oscillator and so spaced apart as to delimit within the vacuum chamber (" the dough- an air -gap of finite dimensions.It has been shown that an ion of charge "e"and mass nut ") of a high -frequency resonant cavity " m " may be liberated from within the forming a gap across which the electrons evacuated chamber and accelerated by ihe pass once each cycle.The cavityis con- high voltage across the D -shaped electrodes. nected electrically to an oscillator and the The magnetic field " H " bends the ion'sFig. 6.-The fundamental components of theelectronsare given extra energyas they eH betatron, shown diagrammatically. pass this gap which is similar in principle path with an angular velocity w = --in-;if to the gap between the Ds of the cyclotron. shown diagrammatically in Fig. 6, where M The principle of phase stability operates the high frequency voltage is of a suitablerepresentsan A.G. magneticcircuitandhere, in that if the energy given to the electron order the ion may be in a resonant conditionMi, M, are cylindrical pole faces betweenis too small the orbital radiusis reduced and it will then be accelerated continuouslywhich isdisposed a vacuum chamber Dand the electron arrives at the cavity earlier so thatitsorbital movement increases in(universally called the glass " doughnut "),than it would have done, and it receives in radiusofcurvature. At asuitable pre-having an electron gun G, and a tungstenconsequence an extra amount of energy from determined radius the ion's path is influencedtarget T ;the entire vacuum chamber beingthe voltage wave impressed upon the cavity by a directive electric field of force, and thesurrounded by exciting coils E E2. ion is withdrawn from the confines of the The operationis analogous to a power(Fig.8). Conversely, if the energy given D -shaped electrodes through an aperture intransformer with a single bar secondary; theto the electron is too large the orbital radius the wall of the D, where itis caused tocoils E E, being not dissimilar. to the primaryincreases and the electron is late in its arrival impinge upon a suitable target. winding, and the electrons within the vacuumat the cavity ;it receives, in consequence, a The type of particle under the ballisticchamber to the secondary current.At thereduced amount of energy from the voltage forces is decided by the residual gas withinstart of the operational cycle electrons areacross the cavity (Fig. 8). the chamber, e.g., heavy hydrogen wouldinjected into the chamber from the electron A schematic view of the synchrotron is cause deuterons to be formed, or heliumgun andaccelerated by inductionforcesshown in Fig.9, and the resonant cavity would provide a supply of alpha particles.dependent upon the changing magnetic fieldR, is shown, the inner and outer surfaces of The cyclotron has been applied most success-within the orbit supplied from the A.C.the cavity are coated with a conducting layer fully to the acceleration of positive particlesmagnet. The electrons whirling in the orbitsuitably designed to reduce eddy currents to are made to undergo many revolutions of thea minimum and the inner layer has a gap (protons and deuterons).Due to relativistic ina plane normal to the electron orbit, changespredictedbythemass-energy,chamber as the voltage increases with time ;across which the bunched electrons under equation particles increase in mass as theirbut since the voltage is alternating in formthe synchrotron action are attracted. velocities approach the speed of light, and anthe electrons need be removed afterI cycle (i.e. voltage maximum) byshiftcoils whichTheVanDeGraaffElectrostatic Orbit Ejector Plate destroy the stability of Generator (7, 8, 9, to) Transmission the orbit and cause the Most of the very early machines for generat- Line Target Chambe- electrons in the elec-ing high voltages were " static " machines, tron beam tospiralthat is to say, they produced voltage owing 10Allustsir,9iin inward and bombard ato the phenomena of static electricity.The tungsten target,thusmost famous of these early machines is the generating high energyWimshurst machine ; itcomprises two X-rays. It has beenco -axial insulating discs revolving in opposite Beam directions with suitable collecting brushes, Ion Source shown by Westendorp Evacuated and Stobley that thisand is to be seen in most college laboratories. Chamber acceleration period ofThe electrostatic generators of to -day are the electrons may bevery similar in their general operation but Amplifier increased by the use ofmuch different in appearance.Otto Von RE Oscillator biascoils,which inGuericke, of Magdeburg, is credited with effect lower the voltagethe invention of such generators, but the zeroline,givinganrealdevelopmenthasbeen duetothe increasedaccelerationresearches of R.J.Van de Graaff, who Pe Circuit 'Waiter Oscillator period, asshowninhasdecided thedesign of thepowerful Fig. 5.-A simple form of cyclotron. Fig. 7. generator which carries his name. March, 1948 NEWNES PRACTICAL MECHANICS 199 The chief advantage of the electrostatic generator, as compared with cascade trans- Target formers and rectifiers,is the low cost per kv., and the only real disadvantage is the low current capacity obtainable. A small type of generatoris shown in Corona Rod Fig.to ; itcomprisesfundamentallya Electron Corona Cap conducting shell in the form of a spherical Gun HV Terminal cap, the high voltage terminal, this is termed the " corona cap " and it is mounted upon an insulating column specifically designed to relieve any high stresses.The insulating ov Equipotential column is mounted upon an earthed frame C': Pings containing a half -wave rectifier transformer combination which sprays, by corona effect, a charge of electricity upon a belt formed li0 Belt from an insulating material (paper or silk), Glass Doughnut (Evacuated) the ascending side of the belt carries the Insulating charge to the upper pulley of the belt drive, Coluren and gives its charge to the corona cap which Ell Earthed acts as a Faraday cage and retains the charge Terininai by induction upon itsoutermost surfaces. 40 To increase the efficiency of the generator (Spray On) the descending part of the belt is sprayed Transformer :Ono with an electric charge opposite in sign to PP Oscillator Rectifier that on the portion of the belt ascending. Fig. 9.-The synchrotron. Fig. io.-Van de Graaff electrostatic generator. The very large generators in high voltage laboratories of modern design, have Van de If one generator is positively charged to,the neutrons diffuse to a uranium rod again Graaff electrostatic generators, incorporatingsay, -roe volts and the other to -toff volts,they are readily captured by 235 U and theacceleratingtube,down whichthethe voltage obtainable across them is 2 X 106furtherfissionsareinitiated.Thevery nuclear bullets are fired under the potentialvolts, a decided advantage. great concentration of free neutrons within the existing between the corona cap and earth. The electrostatic generator may be used topile may be utilised to bombard any element It is usual, also, to surround the corona capaccelerate both positively charged particlesplaced inside the pile and this is now done with gas under pressure, as in the generatorsand negatively charged ones, provided theto obtain radio -active isotopes, which normally at Wisconsin- University and Westinghousesign of the voltage is altered.Electrons havecould not be obtained, and to -day radio- Electric Manufacturing Co.The gas mustbeensuccessfullyacceleratedtoenergiesactive phosphorus and cobalt are produced of over 10r, electron volts and they have provided 2r/06e v X-rays of high intensity forthe treatment of + diseases. CoronaCap + Corona Cap Negative Positive Work is now proceeding + upon the possible use of a Van de Graaff generator in combination with Voltage On Cavity resonant cavity linear Time -- Electrostatic - l' Electrostatic acceleratorstoproduce Generator Generator Fig. 8.-Diagram illustrating the principle ofenergiesashighas No.I No.2 phase stability. 280,000,000 electron volts and even higher. be of an insulating nature or may be Freon (CCI,F2) an organic vapour of high dielectricUranium Fission strength.The use of pressurised gas in this Piles (It) way prevents leakage from the corona cap to the atmosphere and facilitates the use of the The uranium fission pile is a development of work y -f4. , \ generator under humid conditions. undertakenduringthe Itisnot unusual tofind two Van dewar,athigh secrecy. Fig. IL-Van de Graaff generators operating in tandem. Graaff generators operating in tandem, oneWithin a calculated lattice having its corona cap positively charged andof graphite, uranium rods are disposed, thein this fashion for medical research.Other the other having its cap negatively charged,system being arranged to be above a criticalvaluableisotopesarealsoformed,some the potential difference between the two capssize and fission neutrons which escape fromof which arenotto be foundnaturally beingusedfortheacceleratingvoltage.one of the rods pass into the graphite andupon theearth,thebestknownbeing (Fig. xi.) loseenergyrapidlybycollision.Whenplutonium. BIBLIOGRAPHY x. Proc. Royal Society, 136, p. 619, 1932. 2. E. 0. Lawrence and Livingston, M.S. Phys. Rev. 40, P. 19, 5932. 3. Br. Pat. No. 466,836. 4. D. W. Kerst, Phys. Rev. 58, P. 841 (1940). Bristol Freighter Carries Home Damaged 'Plane 5. D. W. Kerst, Phys. Rev. 6o, p. 47 (194/). 6. D. W. Kerst, Rev. Sci, Inst., 13, p. 387 (1942). A"BRISTOL "FreighterlandedatFreighter," said Mr. Hornidge, " without any 7. R. J. Van de Graaff, K. T. Compton, L. U. Van Langley, near London, recently andmechanical help whatever. We got together Atta, Phys. Rev. 43, 149, 1933. opened its nose doors to reveal another air-a labour gang of about twenty Spaniards and 8. E. U. Condon, Elektrotechnische Zeitschrift, 59, craft neatly stowed inside the hold. It wasmanhandled the Consul aboard. The centre - Jahrg. Heft. 39, 1039, Sept. 1938. an. Airspeed Consul, severely damaged in aplane went first, with the fuselage on top, 9. F. H. Merrill, Students' Journal I.E.E., Vol. 9, accidentatValencia andand the wings and engines at the. sides. When 124, 1939. nightlanding to. R. C. Brown, School Science Review, June, 1947, brought back to England for rebuilding. lthe Consul was in, it was impossible to reach p. 369.(Small type for laboratory use.) The Freighter., on charter from' Airworkthe flight deck by walking through the fuse- is. Oliphant, J.I.E.E., Vol. 94, Part I, No. 79, July,Ltd. to Air Transport (Paris), was flown bylage and climbing the ladder in the normal 1947, IL 304. See also -- Mr. P. R. Hornidge, former B.A.C. Test way. We had to get in by means of the a. Betatron,_ by W. Bosley, B.S.C.Journal of Sci.Pilot. Mr. Hornidge, interviewed on hisemergency entrance hatch in the port nose Inst., Vol. 23, No. 12, Dec., 1946. return, described how he found the Consuldoor." b. Atomic Artillery, G. E. Review, June, 1947. on its back at Valencia airport, where it had c. Why Smash Atoms? (Pelican Book), A. K. Solomon. overshot the landing strip and turned a som- The Freighter was chartered, added Mr. d. Atomics, Power Plant Eng., Sept, 1945 -March, 1946. ersault. Noseandcockpitwerebadly Hornidge, " because it was the only aircraft e, Smyth's Report, 1940-45.A general account ofsmashed, but the fuselage and wings werecapable of doing the job." Loading took the development of methods of using atomic energy for military purposes under the auspices ofreasonably intact. three hours ; unloading, three-quarters of an U.S. Gov.(H.M. Stationery Office, London.) " We loadedtheentirejobinsidethehour. 200 NEWNES PRACTICAL MECHANICS March, 1948 A Circular-sawBench Constructional Details of a ,Folding Saw Bench for ,the Amateur's Workshop By W. BADDELEY

IT sometimes happensthatthehomecut to Thlin. long by Sin. handyman goes to his workshop desiringor 4in. broad.The leg and to start making some piece of furnituresupport(A)can then be or other structure built of wood, only to havefixed in position as in Fig. i. his enthusiasm damped .considerably when The length of theleg he finds the timber has to be cut out byshould be such that when in hand saw. theerectedpositionit The remedy is fairly simple if he is willingshould press the horizontal 33" to utilise a few evenings and to lay out asupport against the under- comparatively small sum to construct theside of the bench.This small power saw described in this article. pressure, coupled with the The small outlay will repay him manywing nut fixing (C), helps times over in labour and time saved. tokeepdownvibration My own workshop, like most amateurs', isduringoperation and very limited in space, and the mainobjectioncounteracts the strain of a to installing a circular -saw bench lay in thebelt drive. amount of floor -space it would occupy.This was overcome by making the table fold underThe Saw Table the workbench when not in use. This is shown in detail Fig.t shows the two positions. in Fig. 2 and, as will be The materials required should be fairlyobserved, Nn.timberis easy to acquire, and include the following : used.The type of wood One electric motor (a or h.p.). isnot important but if a One circular saw (6in. dia.). hard wood is used a much Enough timber for the folding supports andlonger life can be expected 1 table. and the chance .of warping Four aluminium castings. reduced. Two pieces of round bright mild steel The table bars shown in (iin."andin. dia.) and some wood screws.Fig.2arescrewedand One piece of bar brass (lin. dia.). glued to the under -side of Fig..-Side view and plan of the folding saw bench.

Section '.4;'4. The table, when built up, should be planed fiat and smooth on the top, and the slot for the saw cut out. The whole assembly can now be given a coat of shellac varnish.This is much better Yy than paint, as the surface is not so sticky. The Saw Spindle and Bearing These parts are the most difficult to make, as they have to be finished fairly accurately to functionproperly. A lathe will be necessary Bearing Block' to turn the spindle and bore out the bearing.

. ..----._------,. Fig. 2.=Section, side view and The Bearing (D) ' - _ L- I plan of saw table assembly. As shown in the exploded view in Fig. 3, this consists of a piece of lin. diameter bar ji 9 9" brass 41 in. long. Mount this in the self - thetopandsoplaced tocentring chuck, face the end and drill out i 1 I -- ,--__A,------'- i + 1 -1- --- I- tFor Saw register the top's position in 32in.diameter, afterwards reaming out to I _ ------1 F I --` II" relationto the tableframe. Reverse it in the chuck and : lin. diameter. _1._ , leatF-6' --IPi The top of course is onlyface off the other end to 4in. long. 12" screwedtothe frame,not e+++---'--- glued, as it has to be removedThe Spindle (E) ; ----_____-____ This is made from a piece of mild steel , , , ntl- from time to time to remove _,._:..-; , ,p4,L , _, ,LJ Oil Hoiii4------; Itis turned ! -4-- I 1 the saw. Tin. long by Jin. diameter. -.....,--i- -, -77-1- , V Oil Hole Saw 54

, ,14.431116..ILLLLaillW1114111.

II Whit Nut rt 1.14. Washer B "ItfPolleyDie 441, 11/4 To SuitMotor The dimensions given in the drawings have _Speed been taken from my own saw table, but obviously the dimensions of the supports will /3Die 7rz. havetobealteredtosuitthereader's requirements.

Construction Recess For -- The main support (A) should be made from Bearing riood On. thick cut to 3cin. long by about j''whit Thread /7.1, Fig.3.-Detailsof saw gin. broad. spindle, bearing block and The Leg (B) driving 'pulley. The leg (B) is made from wood tin. thick March, 1948 NEWNES PRACTICAL MECHANICS 201 between centres to the sizes shown, care being theadjustableguideshownin taken to ensure a good running fit in the Fig. 4. bearing. It is a simple arrangement and can be built up in the most con- The Pulley (G) venient way for the constructor. This component is intended to be made My own arrangement consists of in aluminium and can either be machined i" a t2in. length of tin. diameter mild from the solid or from a casting. steel (part (L)) fixed rigidly with The diameter of this pulley is determined grub screwsin the two brackets by the speed and diameter of the driving which are screwed to the table.The pulley,but the saw speed to aim atis brackets are aluminium castings. 1,500 r.p.m. The following formula will give the correct diameter of pulley : The Sliding Guide (J) Diameter of saw pulley equals : This is also an aluminium casting, which isdrilledfin. diameter to Dia. of driving pulley x r.p.m. of driving pulley allow it to slide along thein. bar. r.p.m. of saw pulley It is locked in any desired position For the drive, bin. round leather belting by the milled -head screw. is used. Part (K) is a piece of hard wood If shafting is not already installed in the finished to size and screwed to the workshop it would be advantageous to do it slide.This part is made in wood now, as a variety of tools can then be driven foreaseinfixingangle cutting from the same motor. attachments, etc. Theideaofa circular -saw The Bearing Block (H) ' folding under the work bench is Hard wood should be used for this block not new, but I have endeavoured which has a cradle cut in the top to hold the to give the reader something con- spindle. bearing, while the small clips made crete with which to build his own of strip steel 315in. thick are used to anchor it. machine. The block is then screwed and glued to Various gadgets will suggest them- the main support in the position shown in selves to the constructor for making Fig.2. unusual cuts as he becomes familiar This completes the saw table except for with the saw. Fig. 4.-Details of the sliding guide.

men recently demobilised from the Services, since it is helping them to regain touch with the portable electrictool industry, and to Trade Notes catch up with developments in the design and production of " Wolf " electric tools. " Electro-Lake" Toy worked from a2 -volt accumulator, which, ANOVEL and instructive toy, recentlyof course, will supply the necessary currentation of the basic principles of sa'esmanship placed on the market by Quin Medfor a longer time.Additional magnetic boatsapplied to portable electric tools and visits ResearchProducts, 2, PortlandRoad,are obtainable. to the works.The second day is devoted Holland Park, London, W.11, takes the form We understand that the retailpriceofto the uses for portable electric tools, fol- of a miniature circular lake, complete withthe "Electro-Lake," complete with batterylowed by demonstrations, and the third day lighthouseandrockfoundation. By anand including purchase tax, is a to after -sales service, packing and presenta- ingeniousarrangementofhiddencoils, tion. which are energised by an ordinary 3 -voltPeco-Way " 00 " Gauge Track dry battery, a tiny ship placed on the water A unique and realistic, form of " 00 " can be navigated in different directions bygauge track has been designed by Messrs. pressingbuttonsontheswitchbox,,as Pritchard Patent Products.The new track, shownintheaccompanyingillustration. which is true to scale with a correct sleeper Two model shipsareprovided withthe and chair spacing, has a very pleasing appear- outfit, one having a tiny permanent magnet,ance and is extremely easy to construct.It Club Report while the other gives an added interest, and isnotexpensive,andnosolderingis Eccles and District Model. Engineering can be moved by means of the controlledrequired for straight and curved rails, and Society .boat.(This second boat is not shown inonly a minimum of soldered joints are used the illustration.) in the point constructTon.Full particulars of talks, etc., up to the The lighthouseisprovided with a bulb andinstructionsforbuildingthisnewPROGRAMMEend of March, 1948 : and will flash when the switch buttons are" 00" gauge permanent way are given in pressed. Asanalternativetothedry anillustratedbookletentitledPeco-Way, February 29th : InternalCombustion batterymentioned,thetoycanalsohe which can be obtained for sixpence fromEngines, by R. 0. Harper :This talk should Messrs. Bassett-Lowkebe particularly interesting.Mr. Harper has Ltd., 112, High Hol-unrivalledexperiencewiththeseengines born, London, W.C.t,of all sorts, shapes and sizes.His motor where supplies of allexperiencegoesbacktothedays when the accessories areeach trip was an adventure and the engines available, and a dem-did live up to their name of " infernal " onstrationsectionofcombustion enginesstill given to them by the track is on view. some of the steam fans. Portable Electric March14th :Plansforthis day are Tools Refresher rather vague at the moment.It is hoped Course to arrange a visit to some place of interest Messrs. S. Wolf &such as a colliery or a power station.Details Co.,Ltd.,manufac- be issued later. turers of "olf" Port- March 28t11: Pattern Making. No lecturer ableElectricTools,has yet been arranged for thistalk. It have instituted a series is,however, hoped to 'get Mr. Meadows, of3 -day coursesforof Manchester, who was by trade a master salesmenengagedinpattern maker. the tool and equipment trades. All the above talks will take place in the The course isClubrooms, Eldon Place, at it a.m. proving ofparticular Hon. Sec.,W. J. Thompson, 1.6, Prestwood interest to those sales-Road, Salford, 6. 202 NEWNES PRACTICAL MECHANICS March, 1948 Tubular Furniture How to Design and Construct Your Own Without Welding

By GORDON HOWL FURNITURE to -day isat a premium, both new and second-hand, therefore exacting planning is needed to pro- vide a tasteful and well-equipped home. A house with the bare necessity of a table to eat from and a chair to sit upon will for- ever remain just a house. To make a house a home the personal touch is required, and to provide nun -essential but desirable fur- nishings, the householder often constructs them himself. Wood being soscarceothermaterials have to be sought to provide the accessories to the home, and metal tube, hard asbestos board and canvas have been found to be good substitutes, requiring little or no timber when constructing. Such substitutes are easy to obtain and moderately inexpensive. One of the benefits of making one's own furniture is that it can be designed to per- sonal tastes and requirements, and with this in mind, specific dimensions for the furni- ture illustrated have been omitted, so as to enable the reader to adapt the design to his ownparticularrequirementsorcircum- stances. In Fig. 5 a variety of designs is depicted to show the adaptability of this type of con- struction. Fig. 5.7 -Some typical examples of tubular furniture. former wheel (B) is retained by three woodthe " vee " of part B and against the peg (G). The Bending Fixture Smooth, clean linesare thekeynote ofscrews gin. long spaced at intervals of 12oThe follower wheel is held in position against tubular furniture, and to make the bendsdegrees on a gtin. P.C.D. the tube and the pin (E) is dropped in.Im- consistent a fixture, simple to construct with- Lines are scribed on the wheel with anmediately pressure is applied the tube will be out forfeiting its efficiency,is required forinclusive angle of 90 degrees as shown infound to be locked in position between the bending the tube cold. Fig.2. former wheel and the peg (G). The fixture shown in Fig.tis economi- To avoid the follower wheel (C) binding Theactualbendingofthetube is cally constructed and 'adequately suitable foron either the handle or the base board aexplained in more detail in the paragraph on making the gin. radius bends. It will be /t6in. clearance is given at the bottom face"Bending the Tube." noted that this is the mean radius, and allow-and a / r6in.by tin.diameter shoulder After the tube isbent, the removalis ance forthisfact has been made in theat the top face.The wheels themselves willsimply effected. by extractingthe pin (E) fixture. not touch but will be in connection onlywhen the wheel (C) will drop away. All other The bending rolls are mounted on a hard-through the medium of the tube.For thisnecessary details and dimensions for con- wood base (A) 8in. square by tin. thick. Thereason the centre of the roller for measur-structing the fixture will be found in Figs. ing the " vee " in theand 2. .4 followerwheelis /t6in. out from the face. Design and Bending /////1/A The two wheels are It is desirable, as far as possible, to make connected by the pinsthe furniture from one continuous length (DandE)passingof tube with only one joint.Naturally, with throughthehandlethe larger constructions this will not be pos- . (F). The grip of thissible, and one will have to resort to secondary 4At 45 handleismade fin.joints. In such a case itis advisable to wide to fit the insideplace the joints where they incur the mini- 4,1 8 diameter of the tubemum of strain and are least conspicuous. and to facilitate extra The articleunderconsiderationshould leverage,if necessary,first be drawn to scale and dimensioned, par- by fixing a length ofticularly the straight portions, for these are tube on the end. the setting dimensions.If the workshop is To operate the fix-large enough itis a great asset to lay the At 45 I ture, insert the tubes inplan and elevation out to full scale in chalk

1,(1 Ns. fzz/.///////4

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L" 5 Alt 45 -606Cha. D' Fit Fit 1" Fig. I.-Sectional ele- vation and plan of the 3 bendingfixture. Fig. 3.-Sectiohal view showing theconstructionof the joints. March, 1948 NEWNES PRACTICAL MECHANICS 203 done after every bend,using the above method of construction. 4bia /6 or the job will not be From the sketches it will be observed that /6 Roller Dia, square at the finish, andthe general tubular construction follows the /4\ jointing will be difficult.lines previously explained, therefore a brief 90 outlineof the not -so -obviouspoints need '4 Jointing only be noted, suchas thefixing of the The joint shown incanvas, etc. Fig.3,although very The general dimensions of any object it is ,ifto/ler Dia. 4 03" al- Dia. Ream. simple, must be accu-desired to construct can readily be obtained rately made togivea from any standard work on fdiniture con- Scribegood finish to the con-struction.In a number of cases the dimen- Drill And Clink Lines " struction.. sions may be limited by thematerial to For Wood Screws After the bending ishand, and the design would then be con- completed itisadvis-trolled by virtue of the necessity to comply able to try the job onwith existing fixtures. the drawing and mark offthejoints,cutting-Desk 120* away any surplus tube. The top consists oftin: thick unplaned The ends ofthe tubeboards battened together by positioning the mo° are then squared up inbattensdirectlyoverthemiddle ofthe the vice and ain. dia-drawers where there is room to spare. Cover meter hole drilled at onethese with a sheet of 3/16in. or,in. hard side of the joint only.asbestos board secured by counter -sunk head tin. from the end. Thescrews. The screws willbe sunk deep jointing peg, Sin. longenough to allow a facing of plastic wood 43" Dia. 2 Da. (Fig. 3), is turned to beover each one.The whole should then be R. Fit a good drive fit in thesurrounded by plain bevelled beading, which I? Fit F-4 2,; tube.The B.S.I. givecan easily be fixed by panel pins. When this Dia the inside -diameter oftop is painted it will form an ideal surface MCI the tube at .6o6in., butfor writing upon.If a more expensive job At 30°--1 itwill be found to beis required it can be effected by covering the g At F.,',_16_3_,4 - 4Dia.A Dia veryrough indeed ;top with American cloth or leatherette prior , D. Fit 30° therefore, inthis case,- to 'beading, and the beading finally stained. D G to fit by trial is .a safer The construction of the drawers can be methodthanworkingobtained from any woodworkers manual or 4 Dia. - Dia. Ream 5' Ream to a micrometer.Theaset ,of drawers. may be availablefrom ATLI peg is drilled with a ,in.which the basis of a design Can be obtained.' _0 diameterholeatoneThe drawers arc set at the tangent of the 1. end only, and carefullybendinthetube,thusgivingaspace 3"Crs.- driven into the tube tobetween theset of drawers and the desk i" matchupwiththetop, which is very useful for letters, writing 21 existinghole. Ifthepaper, magazines, etc. holes donotquite If the desk is made to normal prciportions, - fmatch tool, up a as the back of the drawer case -can be adapted to shown in Fig.4,will accommodate books of reference and other !Rad. be found very useful forworks as the actual drawer will only occupy passing through thepart Of the full length of the desk. 8" 2 holesand pullingthe jointing peg intoline. To fix the drawers and top the frame -is Fig. 2.-Component parts for making the bending fixture shown in Fig. When the holes are indrilled and countersunk in the most incon- line,secure thejoint-spicuous positions to' take stout wood screws. upon the workshop floor.The views willing peg to the tube by driving a ,in. dia- be quite legible if superimposed upon eachmeter silver steel dowel through, leaving itChair other, for certain lines will coincide. protrudingeithersideuntilthejointis Thetubularconstructionofthechair The tube chosen is lin. outside diametercomplete.To finish off the joint, grip thedeviates slightly from the otherfurniture. electricalconduit, and shouldalwaysbeother end of the tube in' the vice, drive theThe top of the back is bent at an angle of bent with the seam inside the radius to mini-free end of the peg in, and drill both tube 20degrees to 3o degrees so, that the sitter's mise the risk of splitting. and peg on assembly, making secure withback takes its support from the canvas and To commence thebending, markthe another lin. diameter silver steel dowel. Tonot from the tube. straight portion from the 'joint to the firstfinish, saw off the protruding ends of dowels' The canvas seat and back rest are iden- bend andinsertinthebendingfixture,and file flush with the surface of the tube. tical in construction and differ only 'in size. matching the mark with the 'first scribed line The details of the seat as now given will, and square up with the stop peg.Bend atFinishing apply similarly to the' back. 90 degrees with a firm, even pull.Do not The finishing,, whether paint or electro- Fig. 6 shows a section through the anchor bend too fast or jerkily as this is liable toplate, depends upon the material of the tube bolts. lose the location. Still keeping the tubeand individual taste, but if under pressure by hand, clear the handle the tube previously Sail Eyelets And and mark the tube in line with the secondmentioned isused,all Washersclosed scribed line on the former wheel. Thistheoriginal covering fixesthe point from which to mark thesuchas paint, lacquer, second straight portion. From this mark,etc., should be stripped place on the drawing, mark the next straightoff and the tube care- portion and bend as before.It will, in allfully polished with fine probability, be found that after this bendemerycloth. T h e the straight portions do not lino up, but theseundercoat of lead paint can easily be set in the vice.This must beshould now be applied and left to dry.A fur- Fig. 6.-Section showing the assembly ther undercoat can be of anchor bolts for the chair seat. 2/,2 given if necessary. The finishing coat should be of a good, hard gloss enamel paint. Typical Examples of Construction Sphervca/ The furniture shown Rad End .245" Dia in Fig.5suggests the Fig.4.-Drift forliningup theholes forvariety of articles which Fig. 7.-Method of slinging canvas for tinting. caneasilybemade, the deck chair. 204 NEWNES PRACTICAL MECHANICS March, 1948 Two lengths of straight tube are cut fromends with strong cord to finish a durablethe 'base of the legs. This can easily be the same stock as the chair, and are madeseat. achieved by cutting a piece of garden hose about 3in. shorter than the length of the The back is treated in a similar manner. into four tin. lengths and splitting them to chair.The ends are plugged with turnedDeck Chair clip round the tube, making fast with a good wood or metal buttons afterthe tube has The deck chair canvas, ready for fitting,cement. been drilled.The tubes should then be setcan be bought from any of the leading storesDressing Table Seat inposition with the chair, and markingsand fixing should be made either by sail eye- made for the two anchor bolts to be drilled.lets or by sewing ; the former method being This is merely the basic construction 'fitted the stronger job. with a padded seat secured by wood screws The holes in the chair should be about When folding over thefrom underneath. With a wooden top it lin.diameter and those -in theseat 'tubetube make sure of a long angle as shown in Fig. 7 to prevent the canvas ripping on thebecomes a stool, or by making the construc- 5/16in. clearance diameter.The length oftop edge. tionlarger,withanappropriatetop,a canvas should be such as to allow for lap- pleasing coffee table is the result. ping round the tube, and to eliminate fray- To lock the deck chair angle plates should be made and set on the chair to the desiredConclusion ing the two outer edges should be bound. angle, and fixed by screwing in to the tapped Mark off the positions of the four eyelets,tube. It will be understood that the chair Finish is very important for itis imper- two of which will coincide with the anchorfolds opposite to the usual standard practice.ative that the completed article be pleasing saileyeletsandwashers to the eye. Pastelshades of hard gloss bolts. Tucker Ironing Board ,. enamel are very effective, contrasting with will be found most suitable for the jc,b, and The top of the ironing board is standard.the non=metallic parts of the furniture. can be obtained at most ironmongers.CutThe back leg is allowed to swivel by run- If the frame of the desk is bent from pol- the holes for the eyelets through which thening jri two conduit clips and the foldingished copper tube with a sheet aluminium anchor bolts pass and fix in position. Com-and standing positions may be secured bytop, it will be found to be very effective. plete the seat by screwing in the 5/16in.Terry spring clips. Naturally the finish will depend, for the Whit, round head bolt and close up the lap To prevent theironing board creepingmost part, on the other furnitiirein the with four more eyelets.Sew up any loosewhen in use, it is advisable to fit rubber to room.

to within the maximum accuracy of one's skilland one'sinstruments.Inpractice, Letters from Readers though not in theory, this solves the problem. Hot-water System I missed the May -June issue, but K. R.--ARTHUR B. THOMAS (Manchester). SIR,-The article in the January issue bySaillard's construction, reproduced and proved [This correspondence is now closed.-ED.] Mr. Burdett on "Electric Water Heatingby R. E. Brett in the December, issue,is Practice," is very interesting.There is onefamiliar.Unfortunately, whilst angles mayCrystallisation Experiment point, however, which I think would improvebe trisected by this method, the construction SIR,-With reference to the query on page the converted installation shown in Fig. 2b.cannot be effected by Euclidean geometry. 139 of the January issue of PRACTICAL Instead of removing the pipe XY a plugW. W. R. Ball says of it in his " MathematicalMECHANICS, regarding the growing of crystals cock should be inserted, and the new pipeRecreations and Essays,"" Theancientson coal, your correspondent may be interested (dotted lines) installed as shown.This plugdetermined the position of the point B byin the following description of what, I believe, cock is kept shut when the immersion heaterthe aid of the conchoid ;it could also be foundis the original method of producing these is in service and if desired can be openedby the use of the conic sections." growths. when solid fuel is used.Its chief advantage Trisection can be effected within Euclidean The ingredients are :Household (washing) is that it can be opened up whenever it isrestrictions to within any required degree ofblue,'oz. ;ammonia, 202. ;water, 2oz. ; necessary to drain the tank, and it saves a dealaccuracy by repeated bisection.Bisect thered or green ink (liquid),202. ;common of mess draining from a cock on the tank. angle AOB by OC ;the angle COB by OD ;salt,1' --oz. In my house the hot-water storage tank isAOD by OE ; EOB by OF ;and then and When mixed together the resulting solution only 3in. above the bathroom floor, and thethereafter the larger of the two angles intois poured over some pieces of coal in a glass drain cock on the tank is of little use. Iwhich theoriginalangle AOB hasbeendish.The best results are obtained with therefore arranged with the borough councildividedbythepreviousbisection.Thepieces of coal about sin. to I sin. cube, in a to insert the plug cock (whilst installing the1st, 3rd, 5th, 7th bisection gives the sum todish about Tin. to 8in. diameter and about 3in. immersion heater) and the extra cost was very deep. 2, 3, 4 terms of the series small. - 32I -1;8, Growth should be started in a warm room, They have now adopted this method asetc., and the 2nd, 4th, 6th, 8th bisectionand after a few days and subsequently, say, general practice.Great care should alwaysthe sum to 2, 3, 4 terms of the seriesonce a week, a little fresh solution should be taken when drilling, etc., for the heaters be gently poured over the coal. etc.,wheretheoriginal that no swarf or filings are left in the tank, as4-f I6 -f -64--f- 256' Some veryfascinatingeffects may be this causes much of the pitting and rusting,angle AOB is taken as1.Both series areproducedfrom theseinterestinggrowths and a new tank is required wellbefore itsrapidly divergent, and in both cases the limit isand they may be kept-" alive " for many time.-K. T. MuLLocx, M.I.E.C. (Thornton By this ,method any angle may be trisectedmonths.-A. ANDERSON (Stoke Newington. Heath). Trisecting an Angle SIR,-There are many ways of trisecting Ground Controlled Approach forCivilAircraft an angle, but none by Euclidean methods.THE Ministry of Civil Aviation, in making London tpoft htahvee As Derbian has pointed out, Euclidean geo- provision for post-war commercial flying,benefit of unitduringto badth metry allows only the use of an ungraduatedtook account of the many advances in radioweather of lastwinter, and sogain the straight -edge and apair of compasses ofand radar that had been made under thenecessary experience as soon as possible, an unlimited length and radiusrespectively.impetus of war.One of the most fruitfulR.A.F. crew and " Bendix " G.C.A. equip- I cannot agree with Derbian that itis notadvances that appeared to have been madement from Prestwick Airport was loaned to " permissible to transfer any dimensions."was in the radar system known as Groundthe Ministry of Civil Aviation by the R.A.F. It is not on this score that R. Rhodes's methodControlled Approach. Accordingly it wason February 7th, 1947.This R.A.F. crew falls down, but on the more fundamentaldecided that G.C.A. would be installed at keywas supplemented by the first civil G.C.A. fact thatitdoes not trisect angles !Mr.airports in the United Kingdom and used foroperational crew on May 7th, the Ministry Rhodes did not set out his " proof," but onecivil aviation. of Civil Aviation taking over completely on surmises he believes that in any triangle the To thisend " Federal "G.C.A .radarJuly 1st. anglesareproportionatetotheoppositeunitswereobtainedforciviluse,and sides, whereas, of course, it is their sines whicharrangements were made for the Royal Air The operational crew consists essentially are. Force to train a number of civil crews.Theof a " talkdown " controller, a supervisor and R. E. Brett's method in the December issuefirst civil crew started training on January 6th,two directors.The last-named bring the isinvalid for the same reason-it does not1947 ;sincethatdatetheR.A.F.haveaircraft around the circuit of the aerodrome trisectangles.He says that, " Itiswelltrained eight completecrews.There are aon the radar search tubes, line it up on the known that if we divide the base of an isoscelesfurthersixcrewsundertraining. Theapproach path, and then hand over control triangle into a given ratio, say m :n, andMinistry of Civil Aviation started its ownto the" talkdown " controller, while two join the dividing point to the vertex, theG.C.A. DeployedTraining Schoolatgirl trackers have the important responsibility vertical angle will also be divided in the ratioAldermaston Airport on October 27th, and theof relaying the position of the aircraft on the m n."If itis well knots %1itisindeed first three crews to be trained by this unitapproach path to the " talkdown " controller popular fallacy ;certainly it is untrue. completed their course on December 54th.from radar precision tubes. March, 1948 NEWNES PRACTICAL MECHANICS 205 The Conundrum of Coal The Modern Attack on the Problem ofits Chemical Composition FROM being one of the commonest ofanywhere in our attempts to discover theis a very curious metal.It melts at 3o deg. all commodities, coal seems nowadaysreal chemical nature of coal.Nor, for thatC. and it remains molten when held in the to be fast rising to the position of matter,doesthefamiliarexperimentof hand. A silvery -white metal, something like oneofourscarcestarticlesofmineral, heating coal and observing the nature ofaluminium, gallium,ifit were commoner, -wealth.The " black diamonds " of the pastthe gaseous and other products which resultwould have many useful applications both in are nearly literallyestablishing themselvesfrom its thermal breaking -up in this manner.its pure state and in the form of its alloys. as such. Yet coalitself,even inBritain,isnotUnsolved Problems a scarce commodity.Thereisplenty of The problem of the it under the earth.The same applies alsochemicalsomposition in many other countries, whilst in Chinaof coal isa real one. the coal deposits are considered to be almostItisaconundrum inexhaustible. whichstillperplexes There is no doubt, so far as this country chemists and other isconcerned,thatincoal we have our scientists. Butbe- one large source of home -produced power.cause thesolvingat True itisthat small oil wells have beensuch a problem is not opened up in Britain and that these,have considered to be contributed useful, quantities of natural oilbound up withany to -aid our resources.Nevertheless, puttingconsequences of prac- the question of atomic energy apartasa ticalimportance,the matter which has not yet reached the stagequestion of coal's of industrialisation, without coal we in thiscomposition has more country would be bereft of the major portionorless been side- of our civilisation's, power, to say nothing tracked,onlyafew of our lighting and our heat.That, in ascientists havin g nutshell, is the reason why the coal questionworked on the prob- has attained such overwhelming importancelem now and again. inthese modern times and why, in one OrdinarychemicalGalinon, a rare111010/ which melts in the hand. Its oxide is present in way or another, a general solution to theanalysiscanreadily some coal ashes. many problems and perplexities of its gettingshow that the element must ultimately be arrived at. most abundant in coal is carbon, and that, Just how gallium and germanium origin- From a technical and scientific standpoint inaddition,itcontainshydrogen;someally found their way into certain varieties itis a curious thing that the chemical com- oxygen, nitrogen, sulphur, phosphorus andof coal is, of course, quite a mystery.They position or make-up of coal isstill a matter several other elements. must have been present as constituents of theoriginalplantsandvegetationfrom Coalashcontainswhich the coal has been derived since these more than 95 per cent.elements are present in the actual coal sub- of a mixture of fourstance, but their actual significance in this oxides-siliconoxide,connection has never been determined. aluminium oxide, cal- Coals have been roughly classifiedinto cium oxide and irontwo main varieties, the hard and the soft oxidebut,strangely coals.The best known of the hard coals enough, there are some isanthracite. Likeallthe hard coals,it c o a 1 s, particularlycontains a maximum amount of carbon (from t h e Northurnbrian90 to 95 per cent. of this element).Conse- coals,theashesofquently, it gives out a maximum degree of which contain at leastheat when it burns, and usually with such two rare metals in thecoals thereisa minimum of smoke and form of their oxides. flame.Hence, the hard coals are reserved One of the metals ismostly for steam -raising purposes. germanium,arare The soft coals contain from 5o to 8o per substance which is incent. of carbon.Such are the bituminous A lump of .peat and one of coal seen side by, side.Note the fibroussome respectsonlycoals (so called, for they contain no actual nature of the peat compared with the hard, shiny nature of the coal.half a metal because inbitumen).Because they burn brightly they Both substances have a common origin. many propertiesit are employed for domestic purposes and for resembles silicon, a gas manufacture, these coals producinga of much mystery.Itisall very well totypical non-metal and the element of sand.maximum amount of inflammable gas. remark that coal is made up for the most Insome Northumbriancoalashes,ger- part of carbon and 'thatitrepresents, themanium oxide has been found to the extentProducts of Coal end -point of the slow decomposition of longof nearly t per cent. The' behaviour of coal anditsthermal pre -historic forests and swamps.Such facts The other rare -metal oxide found in somedecomposition on heatinghasbeenvery ore true enough, but they do not getus coal ashes is gallium oxide.Now, galliumcarefully studied for more than a century.

These five actual Photographs prove conclusively the vegetable nature of coal.Each photograph was made from a thin section of coal in which cross -sections of the stems and leaves of the original coal forming vegetation are clearly revealed. 206 NEWNES PRACTICAL MECHANICS March, 1948 When an average grade of soft coal is heatedwhich, without actually destroying or chang-been given tentatively.Now, thisresinite in iron retorts to about t,800 deg. F. (982ing the nature of coal, are capable of dis-material is, as its name implies, of a resinous deg. C.) it produces gas, a watery ammoniacalsolving certain portions of the coat materialnature, anditconsistsapparently ofthe liquor and a black tar, a residue of cokeand leaving others undissolved. original vegetable and woody resins of the remaining behind in the retort. For instance, extraction of coal with hotprehistoric coalforests and swamps. An Itisfrom the blacktar(" coaltar ")benzene under pressure results in the selec-interesting feature of these " coal resins " is that so many of the raw materials of thetive solution of some parts of the coal. Otherthat they are seemingly very little altered in modern chemicalindustryinBritainare selective solvents are pyridine and aniline.composition from the original resins present obtained.One ton of coal tar supplies, onChloroform and boiling carbolic acid (phenol)in the material of the coal age.They are anaverage,5gallons ammonia liquor,6 have also been made use of all per -hydrous or rich in hydrogen, and of gallons crude naphtha, 26 gallons light oils,for the same purpose. All ell the original coal -forming materials they 57gallons creosote oil and 38 gallons oftheseliquids(ormixtures are the ones which have undergone the least heavy anthracene oils.The residue com-of them) have been found to degree of change with the passing of the prises about 12 cwt. of a black, brittle pitch becapableofremoving countless centuries. which is left in the retort. definite portions of the coal Itmight be imaginedthatthe abovesubstance and of so effecting " Humic Acid" detailed information would give us some idea arough separation without By the extraction of coal powder with an of the original composition of coal.Unfor- aqueous solution of caustic potash asub- tunately, however, such is not the case. You stance known as" humic acid " has been can no more tell the chemical composition obtained.Without any doubt, this material of coal from a survey of its distillation pro- is not a single acid but a complex mixture ducts than you can picture the exact design of compounds having related properties.But of a building from an examination ofits theinterestingpointaboutthis" humic bombed remains. The black, rocky material acid " (whatever it may ultimately be found whichiscoalisessentiallysuch a very to consistof)isthatifitispresent in complex mixture of carbon, sulphur and greater amounts than 2 or 3 per cent. the nitrogen compounds (all derived from the coal will not coke well and the gas which slowdecompositionofvegetablematters is derived from it will have a high percentage under great pressure) that only the most of carbon dioxide. Allcoalswhich are elaborate, and refined of chemical analytical essentially capable of good carbonisation in- processes canever hope to sort out and variably contain less than the above " humic identify the mixture. acid " content.Hence humic acid decreases Turf or peatisusually said to be coal the fuel value of coal.These " humic " sub- inthe making.Both coal and peat are stancesallcontain nitrogen and they are derived from vegetable matters, but in peat Pressure pot, for the solvent extraction of coal. usually associated with small amounts of a the coalification process has hardly had time neutral, wax -like substance of low oxygen to get under way. You can readily see andactually changing the coal substance in anycontent which can be extractedfrom the separate the fibrous portionsoftheturf, way. coal. despite the fact that they have become natur- In this manner, modern science has recog- The bright coals-those containing maxi- ally matted.But itisa curious fact thatnised some four very definite constituents ofmum amounts of clairain, are considered to ifturf is treated with a dilute solution ofcoal, these being present in all types of coal soft have been depOsited in situ in the areas of caustic soda, the individual fibres swell upno matter whether they are hard or the originalcoalforests, whereas the dull and largely lose their identity, so that the varieties._ the constituentsare:Fusain,coals (those containing maximum amounts of turf becomes blacker and less fibred thanDurain, Vitrain and Each of thesedurain)arenowadays regardedasbeing it was originally.This fact definitely seemsconstituents is undoubtedly complex in itself " drift' materials, the decayed vegetable and to show that turf is " coal in the making,"and is made up of a large number of different Yet, for each indi-other plant material having originally grown yetallefforts to speed on the process bychemical 'compounds. somewhereelseand subsequently having artificial means and to convert turf or peat vidualcoal constituenttheseparate com-drifted and been deposited at distant areas. into coal havefailed.Within the limitsponents must all be related, since they haveThere is plenty of evidence of this contention, of our present-day knowledge the natural apparently similar properties. butitisall of a botanical and geological Coal Constituents . nature, and rather too complex to be brought Fusainisthe mainin here. constituent of the hard, When coalis very finely powdered and anthracite - typecoals. mixed with air or oxygen it acts as a very It is hard andsub - powerful explosive.Many studiesofthe hydrous, that is to say,rate of flame propagation through coal dust - poor in hydrogen con-air mixtures have been made, thissubject tent. Fusainappearshaving received a large amount of attention to have a pronouncedin consequence of its important and, indeed, A split-second photograph of an explosion and pressure wave travelling influence on the cokingvital bearing on measures involving safety through a coal dust -air mixture. qualitiesofcoal,its in mines. presencevery much coalification process cannot be accelerated.reducing these qualities. Scientific opinion, Coalcanalsotakefirespontaneously Hence, from the detailed study of turf andalthough not as yet very positive, is that theunder certain as yet not very clearly under- its reactions we are not very greatly carriedfusain in a coal is derived from the woody stoodconditions. However, the explosive on the road towards the elucidation of thestructures of the original coal -forming vege-natureofcoaldustcombined withthe chemical composition of coal. tation. In very thin sections faint indica-material's proneness to spontaneous combus- tions of the original woody structure can betion, points to the presence in the coal of a It is not possible to analyse coal by sub- very highly reactive constituent or group of jecting it to any process of heating, becauseseen in this component. Next comes Durain.This is the granular,constituents, the nature of which isas yet by so doing the coalisdestroyed. You unknown.If strides could be made in this cannottreatcoalwithAcids,alkaliesorhard, " earthy " constituent ofcoal which givesitadull matt surface.It seems todepartment of chemical science, much might other chemicals, for they, too, tend to alter bedonetoreduce mine explosionrisks, its original nature. decrease the burning properties of the coal. In contrast to this is Vitrain, the coal materialwhich, afterall, present chemical problems Some light has been thrown on to thewhich gives the bright, glistening surface toto the investigator as well as purely physical innerstructureofcoalby makingthin,the mineral.This has a fairly high hydrogen ones. microscope sections of the material and bycontent, for which reason it burns well and subjecting these to close examination. By has good gas -producing qualities. " Liquid Coal" itispossibleto thismeans, differentiate Finally, thereisClarain, another bright The essential chemical reactivity of coal between the coal which has been derivedconstituentofcoalsomewhatrelatedto is shown when powdered coal is suspended from the woody structures of the originalvitrain.This constituent shows its presencein a hydrocarbon liquid, such as paraffin, and vegetation and those which have come frombest as the bright, glossy surface which isis treated with hydrogen gas under a pres- the, more resinous parts of the vegetation. manifested when a lump of coal is brokensure of 23o atmospheres (i atmosphere equals at right angles to its bedding planes, that isa pressure of151b. per sq.in.) and ata Selective Solvents . tosay,tothe planes in which thecoaltemperature of approximately 425 deg. C. The most promising attack on the problemmaterial was originally formed in the earth. Under these conditionsthe coalispartly of coal's composition has been effected by the In addition to the above components oftransformed into a liquid fuel, up to 6o per use of selective solvents. all average coals there isa very interestingcent. of the weight of the coal undergoing There arc a number of chemical liquidsone to which the name of " Resinite " has this rather startling chemical change.,The March, 1948 NEWNES PRACTICAL MECHANICS 207 composition of the " liquid coal " is as yetsition of coal.The one fact which will strikecoal ingredient is, for instance most respon- imperfectly known, butitis mainly ofa the reader who has perused so far is oursible for its gas production, which for its tar hydrocarbon nature and, as such, it is, aftervery great ignorance of the exact nature andgeneration, which for its burning, its heat simpledistillationandrefining,perfectly theprecise chemical composition ofcoal. of combustion, the ammonia ofthe " gas suitable for use as a fuel for oil and petrolSuch, however, is a very definite fact, regret-liquor," and so on. engines of all types. table though it may be. Admittedly,atpresent,such knowledge The mass production of " coal oil " from We know what coal will do, what heat itwould be more theoretical than practical, yet, powdered coal is, therefore, an accomplishedwill give, what power itwill produce andultimately, the practical and utilitarian bear- fact. Its extended application on an en-exactly what materials we may, under givening of this information would be very great larged industrial scale only awaits furtherconditions, obtain from it,yet we lack an indeed.For not only would it enable us to technical development,thecoming ofexact knowledge of what coal is. utilise coal more efficiently and, asit were, cheaper hydrogen gas and, of course, the To say that coal isa carbon compoundto get more out ofit, but also by means requisite commercial and industrial demandimplies extremely little.What we want toof suitable admixtures we might thereby be for this type of oil fuel. know is how the various constituents of coalenabled to effect coal economies which are Here must end our article on the compo-are related to its observed properties. Whichat present hardly dreamed of.

Mathematicsas aPastime The Third Power: ACycloid Toy. By W. J. WESTON ACUBE is a solid figure contained by six'3 raised to the tenth power.The firstis guishes it from all other curves. The property equal squares ;-and, since a side ofs,000 ;and, assuming that you takefive is that the cycloid, being inverted, gives you the' square is at once the length andminutes to fill in ten results on a form, youthe path of quickest descent from a higher the breadth and the thickness of the cube,might be able to accomplish these.It wouldpoint to a lower in the same vertical plane. . the cubical contents equal the third power ofmean, though, more than three days andThe property seems to have been found out this side. The third power is often called thenights of continuous writing.The second,by accident, not calculation.However, make cube. however, 310 is 59,049 ;and 200 days wouldan arch having its base exactly four times its This cube isinteresting. Examine itanot suffice for that. height (or depth) and test the matter. (Fig. 4.) little :the examination may have a bearing One of two similar spheres-two ball - upon your filling -up of football forms. LookA CyCloid Toy bearings or two similar marbles-travels from at the accojnpanying table. You have some ingenuity in manipulating'A to B along the plane surface. The second Perhaps you would like to continue it untilmaterial-wood, or steel, or plastics. You you reach so along the topend down the left-are able, therefore, to make a mathematic- hand side.You see how the table 'is built :al toy that will win many a wager.The 2 has two numbers down and across risingtoy depends upon apeculiar property bf 4 by 2 ;3 has three numbers rising by 3 ;the cycloid. 4 has four numbers rising by 4-and so on. As a wheel rolls along a level surface, each Common Cycloid You have now in each corner the square ofpoint on the outside rim touches that surface, a number :I, 4, 9, 16, 25. You have also inrises to the top of the wheel, then sinks to the each compartment the cube of a number :surface again. And, while the point is rising (2 I-4 I-2), (3+6+9-I-6+3)-andSOon. and sinking, it is being carried at an equal rate along the surface. The distance travelled, 13 23 e 43 53 therefore, between two contacts of the point with the surface must be four times the height 2 .

,. (or diameter) of the wheel. That is to say, the Curtate Cycloid path of the point in space is a curve, the base of which is four times the height. Moreover, the curve comes to a point (or cusp) at each I I 2 3 4 5 end, as in Fig. 1.

The curve differs in its having a pointed (or cusped) beginning and ending from the - 2 4 6 8 I0 curve traced by a point on the flange of a Table for work-wheel. This latter point traces an ampler Prolate Cycloid Fig. 3. 3 6 9 12 15 ing out the thirdcurve and, since the flange keeps pace with power problem. the rest of the wheel, the ampler curve is bound to be shortened.It is shortened by 4 8 12 20 16 its having a loop at each end. As you see from Fig. 4. this loop, a point on the flange will have- Line Of 5 10 15 20 25 no matter how speedily a wheel rolls forward -during an imperceptible time a backward Quickest movement. The path of a point on the Descent Now consider this :four football matchesflange is as shown in Fig. 2. Diagrams illustrating different forms of cycloid. are to be played ; how many forms must you The curve traced by the point on the rimsphere, released at the same time, travels froth fill so as to ensure one form with the actual.of the wheeldiffers,, too, from the curveA to B along the inside of the cycloid. The results ? traced by a point within the circle :this lattersecond, thoughithas farther to go, and Three results are possible in each match ;curve needs bends (or inflexions) to prolongthough it reaches the end of its journey by andwe assume-whatthe home -teamit. The path is indicated in Fig. 3. climbing upwards, gets to B when the first supporters will deny-that a draw is just as The word appropriated to the path tracedis an appreciable distance away. And, if you likely as a win or a loss for each team. Manyin space by a point in the circumference of areplacetheplanesurface withacurved jump impetuously to the conclusion that thecircle as the circle rolls along a straight linesurface, other than a cycloid, you get the same number of forms needed is the number ofiscycloid. The Greek ending-oid,youresult.The sphere rolling along the arc of matches cubed :for four matches it wouldremember, means " being like " :you speak,the cycloid reaches B first. be 43 or 64. for instance, of the anthropoid apes, those A little thought shows the error.Supposehaving the form of man. The cycloid is not' two matches. Then the three possible resultsa circle, nor part of a circle ;it is a curve like GEARS AND GEAR CUTTING of one match must becombined with-a section of the circumference.The cycloid multiplied by,thatis-thethreeresults -with loops is a curtate (shortened) cycloid ; Edited by F. J. Camm. of the second match. The number of formsthecycloid, withinflectionsisaprolate Price As. from all Booksellers or.6s. 6d. by (extended) cycloid. post from George Newnes, Ltd., (Book Dept.), needed is not 23 or 8, but 32 or 9. Tower Noose, Southampton Street, London, There is, you see, a deal of difference Now, the cycloid-the common cycloid W.C.2. between so raised to the third power andwith cusps-has one property that distin- 208 -NEWNES PRACTICAL MECHANICS March, 1948 THE WORLD OF MODELS Luton Model Engineering Exhibition NewType ofExhibition Model Railway Museums By "MOTILUS" THE town of Luton, in Bedfordshire, is well knownasthemanufacturing centre for the popular Vauxhall motor cars and other engineering works; and during 5,1k.451 Mil the past ten yearsits importance has in- Itflt(tt frit creased as a centreforengineering work ffitfOtt S where high skill and accuracy is needed. I have previously referred to the model work done by the Model Engineering Section of the Vauxhall Motors Recreation Club, and that done by the Geo..Kent Model Engin- eering Society:also to the more recently formed Percival Aircraft Model Engineering Society. In December last,a Model Enginering Exhibition was held in Luton at the Waller Street Assembly Hall.This was a combined effort, sponsored by the Vauxhall Motors Re- creation Club and supported by the two other societiesmentionedabove,together with the Aylesbury and District Society of Model Engineers, the Watford Model Engineering Society, the Luton and District Society of Model Engineers, the Luton and District Model Aeronautical Society, the South Beds

Fig. 1.-A general view of the Luton Model Engineering Exhibition, showing the ship section " in the foreground. present work, will be a first-class job. An- other model that was very much admired was afinesin. scale" Flying Scotsman," built by Mr. Forest of the Aylesbury Society. This had been made from castings and draw- ings supplied -by Messrs. Basiett-Lowke, Ltd., of Northampton.Ow:ng to the very compre- Fig. 2.-A gin. working scale model L.N.E.R. "Pacific," built by Mr. A. Woodward of the hensive set of draWags, castings and finished ' Luton Model Enginwring Society. parts that can be supplied by this company, this " Flying Scotsman " is one of ihe most Ship Model Society, and also the SocietyDoone." Mr. George Archer contributedpopular engines for the enthusiast who wants of Model and Experimental Engineers, Lon-the largest locomotive at this exhibition, a scale, rebuilt L.M.S. "Royal Scot " andto make a start on building a real fin. scale don. model locomotive.I would also mention a - At this exhibition, there were over twotender (unfinished), which is being built from231in. gauge " Green Arrow " built by Mr. hundred and fifty models on show, includingthe official L.M.S. drawings. This model0.Tiefenbock,oftheVauxhallMotors locomotives, tractionengines,ships,aero-will be up to Mr. Archer's usual good stand-Society ; when one app -eciates the difficul- planes, etc., and in general they were all of' ard, and itisinteresting to note that thereties under which this model was built, one a very high standard.This must give greatare to be over three thousand rivets in therealises it is a very fine effort. satisfaction to anyone who appreciates thetender alone! Mr. Stokes, of the Luton value of modelmaking as a hobby, and alsoSociety, had on view a lin. scale chassis ofModel Ships Section' as an incentive of interest in accurate andan L.N.E.R. " Atlantic," which, if the fin- Regretfully leaving many interesting loco- well -finishedlightengineering production.ished model comes up to the standard of themotive models still unmentioned, we must The highlight of the show was considered to " be a really marvellous beam pumping engine, the work of Mr. A. Woodward, of the Luton Model ,Engineering Society.This was an exquisite piece of work, and an example of superb craftsmanship.Nor was this the only work of Mr. Woodward that was shown: he also included in his contribution to the exhibitiOn an excellently finished and well - constructed fin. scale model of an L.N.E.R. "Pacific " locomotive (Fig. 2). Passenger -carrying Track The passenger -carrying railway track was as popular as usual, and although Mr. E. G. Ebon's " Hatton Five " was not up toits usual form, it did some useful work. Mr. Dawson Bond's f in. scale " Stanier " L.M.S. mixed traffic locomotive lived up to the high expectations of those who had seen it run- ning on a track before, and Mr. -F. Lane's lin. scale " Bantam Cock " performed splen- didly. Everyone was pleased, also, with the excellent trialrun of Mr. E. W. Fraser's Fig. 3.-A very commendable piece of craftsmanship in wood.An old-time warship made by beautifulGreatWesternSingle;" Lorna Mr. Soddy. March, 1948 NEWNES PRACTICAL MECHANICS 209 pass on to have a look at the shiplovers' sec- instruments Mr. Hellewell had made were thing for his young son, after seeing how the tion.Here again, the standard of work was a- 9.5mm. cine projector, a microscope, and little fellow was intrigued with a model lorry high and this has no doubt been helped byan optical projector. his father repaired for a friend.Being con- the fact that the secretary of the New Luton The juveniles should always be encour- nected with road transport, Mr. Short natur- Ship Society, The South Beds, Mr. T. Wil-aged in these mcdel exhibitions: they may ally turned to a vehicle with which he was lots, is an outstanding modeller in the build-be the prizewinners of the future. Full familiar, and the illustration (Fig. 5) shows ing of waterline ship models. Mr. Willots hadcredit should be given to the twelve -year -old the Leyland tipper inits elevated position, on show many beautiful examples of hisboy, Master Donald Crisp, who had made displaying to advantage the nice proportions skill, neatly displayed in small, glass cases. a model horizontal engine:an outstandingand details of the prototype.The model is Also in the ship section were some goodpiece of work for a young person of this approximately one -tenth full size and has an models of ships by Mr. S. Shelton, of theage (Fig. 4)., overall length of just over 2ft. bins.Made Percival Aircraft Society. Mr. Shelton has Therewereseveral tradeexhibits andof sheet copper and steel,itis driven by a a keen eye for detail and his artistry is evi-special mention must be made of the excel-gramophone motor which propels the lorry dent inhis model work. Another ship\lent display by Messrs. Gibbs and Dandy at about walking pace and also operates the modeller whose work was worth noting wasand Lushington Tool Company. This in-gear pump toelevatethetipper. The Mr. J. Gurteen, of the George Kent Society,cluded small machine tools, hand tools; and wheels are Olin. diameter and are fitted with who showed a unique and fine model slfp,many useful accessories that are so soughtreal scale model rubber tyres, supplied by 54in. long and made entirely of postcards, afterbytheamateurmodelenthusiast. the India Tyre Company.The radiator is obtaining, even in this seemingly awkwardModelmakers are Specially favoured by theconstructed of small brass tubing, to scale, medium, some beautiful detail. Old-timemanaging director of this company, Mr. R. and the head and rear lights all operate from ships werewell represented, andspecial Dandy, who isa modelmaker himself anda dry battery.The cab windows are fitted mention must be tnade of the old-time war- appreciates their requirements. with glass and the doors can be opened and ship model by Mr. Soddy (Fig. 3), and also My general impression of the exhibition shut.Owing to the limited amount of spare Mr. Bratcher's excellent model of the paddle -was of the extraordinary high standard oftime Mr. Short has for his favourite hobby, steamer, Balmoral. work shown; you could have counted on the the construction of the lorry took him ten Near the ship section was a special stand fingers of one hand the few poor models that yearstocomplete. This isnot the only model he has made: one of his first attempts was a 21in. gauge L.N.E.R. " Flying Scot," built from drawings, castings and fittings purchased from Messrs. Bassett-Lowke, Ltd.,. of Northampton.Mr. Short told me that this locomotive has done 4i hours continuous working, the boiler being fired by methylated spirit, a constant water supply being kept up by an axle -driven feed pump. New Type Exhibition Model When seatravelbecame popular with thepublicgenerally,shipping officesand travel agencies in towns began to use models toattractprospectivepassengerstotheir

Fig. 4.-A remarkable piece of work by twelve- year -old Master Donald Crisp.' This working modelhorizontalsteamenginewasmade entirely by Master Crisp, with the exception of the boring of the cylinder and the making of the reversing screw, which was done by his father. of general engineering models. Among these were tools such as drilling machines, grind- ingattachments,etc.,and also horizontal steamengines,verticalengines, petrol engines and traction engines. As an en- couragement to young engineers, some ex- amples of tools made by Percival Aircraft apprentices were shown on this stand. The aero section was in the capable hands of the Luton and District Model Aeronau- tical Society. The detail and high standard of work on the aircraft of Mr. Miller, a Fig. 5.-A large model of a Leyland hydraulic tipper, over 2ft. 6in. long, built by Mr. G. W. member of the society, is truly remarkable. Short, of Kettering.(Photo by Speight of Kettering.) The large number of trophies this society had on show also displayed the high averagewere displayed.The only complaint I have liners.Such models were generally made in standard of their work. One must alsois that this exhibition cannot be held at closer a special department for that purpose at the congratulate the makers of the fine smallintervali than two years! However, whenshipbuilders' and were often included in the compression ignition engines. The secre-we consider the spare time it takes to pro-contract for the ship.Originally they were tary of thesociety, Mr. Clark, isavery duce models really worthy of an exhibitionfull hull models and showed, not only the helpful and genial personality, and the model of this calibre, we realise that a bi-annual plan enormous amount of detail on the decks in aircraft men generally appear to have madeis perhaps sound policy. those early days, but also the accurate shape enormous strides in both design and work- ofthehull,rudder,propellersandall manship. Model Hydraulic Tipper " under -sea " features.In later years pub- Mr. J. Hellewell, of the Vauxhall Motors On show at a model exhibition in Ketter-licity experts considered that the waterline Club, in addition to a very good model trac-ing, Northamptonshire, last November, wasship model was more realistic for the would- tion engine of tin. scale, on which the geara model Leyland hydraulic tipper, made bybe traveller and had them made, usually by cutting had been done in his own workshop, Mr. G. W. Short, of Kettering.I had thespecialist firms, showing only that part of and an equally fine Gauge 0 locomotive, also pleasure of meeting Mr. Short some timethe ship which appears above the waterline, contributed items not often seen in a model after the exhibition and was interestedin for which purpose the model was displayed exhibition:they were three optical instru-the story he had to tell regarding this first-on an artificial sea-a calm one, needless to ments which, to function properly, must in- classpieceof model work. Mr. Shortsay!Later still, it was felt that a more inti- corporate accurate craftsmanship.The threeoriginally had the idea of making a play -mate and personal approach would be better 210 NEWNES PRACTICAL MECHANICS March, 1948 and models were made of the interior of the of course; forgetting the excellent collection 6in. long, you can measure up to. 2 tit.in shipandalsoofindividualcabins. I ofmodelsintherailwaysection ofthe Gauge o and 37ft. in Gauge oo.On the mention this only as an introductiontoa Science Museum, South Kensington. Myreversesideareinchesin1/16thsand model I saw recently in the London offices of reference, however,isonlytomuseums 1/12ths, and also the metric scale for com- the Blue Star Line, in Lower Regent Street. devoted entirely to the railway world. parison.These rules can be obtainedat This was a large-scale reproduction of one the London and Manchester branches of ofthecabinsontheirnewship,theModelmakers' Rule Messrs. Bassett-I-owke, Ltd., or direct from Argentina Star. Sheisthefirstof four I am pleased to see that Messrs. Bassett- Northampton by post, price 9d. 12,00o -ton passenger -cargo vessels of entirely Lowkc, Ltd., have re -issuedtheir pre-warERRATA.-The modelbridgemadeby new design and sailed on her maiden voyagemodelmakers' ivorine rule.This is a repro - Mr. B. Timmins, described in the January in Junelastyear. This vessel was built in the yards of Cammell Laird at Birken- head, and has many new features in the planning and equipment of theship, with accommodation for sixty first-class passen- gers,allin single or double cabins.The model I saw exhibited was to a scale of Sin. to the foot, or one -quarter full size, and it incorporated some new ideas in the presen- tation of a ship's cabin (Fig. 6).Instead of one of the blank walls being removed and the portholes being represented on the far side, the wall abutting the promenade deck was chosen for removal and its place taken by a sheet of glass, with the position of the rectangular ports just indicated to show their height and -size.The passenger can thus have abetter idea of the position of the cabin, as this method emphasises the fact that the ports do overlook the open sea.The cabin selected in this instance. wag a two - berthone,withprivatebathroom:every minute detail of furniture and modern fit- tings was shown, even down to soap in the bathroom and miniature books on the shelf ! Indeed, it was one of the most attractive and fascinatingship cabin modelsIhave yet seen, and my congratulations go to Messrs. Fig. 6.-A new type of exhibition model by Bassett-Lowke, Ltd., of Northampton, showing Bassett-Lowke, Ltd., the makers, who were the interior, as viewed from the deck, of a two -berth cabin, with private bath.The model is responsible forthis novel display. Ican seeing of one of the cabins on the new Blue Star liner," Argentina Star," engaged on the South American imagine would-be passengers,after service. thispreviewof the cabininwhich they might rest and sleep during the sea voyage,duction of the previous well-known friend issue, was built at the instruction of the hurrying into the Blue Star offices and book-of the modelmaker and model railway fan, managing director of Messrs. Painter Bros., ing this very accommodation: but there is noexcept that, instead of measurements being Ltd., of Hereford.It was loaned by that need for this, as all the cabins are equallygiven for Gauges o andr,they arefor company toBritishInsulatedCallender well fitted and planned, although some areGauges oo and o.This is a sure indication Cables, Ltd., for inclusion in their exhibit necessarily without private bathrooms. that oo Gauge is now more in use than at the Engineering and Marine Exhibition Minch. Gauge.Although the rule is only at Olympia last year. Railway Museums I have noticed that the daily press recently has been advocating the establishment of a railway museum in this country.I wonder, now the railways are nationalised, whether the Government will look after this import- Books Received ant duty and endeavour tomaintain,forElectric Wiring (Domestic).Edited bycame into the possession of the Highland future generations, a record of the progress E.Molloy. Published by GeorgeRailway from its incorporation until its final that has been made in rail travel, in view of Newnes, Ltd.240 pages.Price 7s. 6d.absorption. Locomotives are listed in the class the fact that we were the pioneering country net. and type of .their original construction, and in railways.The Germans had a magnificent THIS book is intended for persons engagedarcidentifiedbytheiroriginalrunning museum at Nuremburg in pre-war days, with in electric wiring and electrical con-numbers. There are over one hundred models of every description of locomotive andtracting work, and for plant and maintenanceillustrations, with representative locomotives rail equipment, including sections of track,engineers in works and factories. Youngfrom almost every class.Numerous line examples of bridges and everything connectedmen employed in the service or maintenancedrawings are included for the benefit of model with German railways.As farasI amdepartments of electricity supply companiesrailway enthusiasts. aware, thereis no museum devoted exclu-will also find in this work a valuable supple- sively to railways in this country, except thement'to the ordinary text books, as used for one at York.This museum is mostly con-the theoretical study of electrical work.It cerned with L.N.E.R. examples, butisa explains in a clear and concise manner the Our Cover Subject brave effort and well worth avisit. It in-most up-to-date methods of electrical installa- DEMANDS from allthe world markets cludes actual, historic locomotives, such astion work. A chapter is devoted to the various are being received by British manu- the Great Northern Railway single wheelsystems available, and in separate chaptersfacturersformobilecranes,excavatprs, engine No. r, built at the G.N.R. works inthe more important systems, such as themachine shovels, etc.With a tremendous Doncasterin187o,anddesigned byP. conduit system, are dealt with.The variousamount of engineering andreconstruction Sterling :also the 4-4,-2" Henry Oakley,"systems of surfacewiring arealsofullywork in progress in all parts of the world, No. 99o, built at the G.N.R. works in 1848,described. Other chapters deal with thethere is a boom in these mechanical labour- to the design of H. A. Ivatt.Another is thewiring of asmall house during erection ;saving devices.One of the biggest British L.B. and S.C. Railway locomotive, " Glad-the fitting of additional points ; and efficientmanufacturers is the Ipswich firm of Ran- stone," built at the Brighton works of thatearthing.The book is well illustrated withsomes and Rapiers, Ltd., and they have just company in1882,tothe design of Wm.line drawings and half -tones. received an order for theworld's largest Stroudley. Last,but by no means least " Walking Dragline "-an excavator-which important,the famous G.W.R. " Cityof A History of Highland Locomotives. Bywill weigh 5,500 tons, and have a boom head Truro," built at the G.W.R. local works at M. C. V. Allchin. Published by Railwayhigher than Nelson's Column.The illus- Swindon:intheyear1904thisengine Hobbies, Ltd., 86, Essex Road, South -tration gives a view of one of the general achieved the highest authentic speed recorded sea, Hants.72 pages.Price xos. 6d.engineering fitting shops, showing preparatory up to that date for a railway train,102.3 post free. work being carried out on the heavy machinery m.p.h., during part of the run from Plymouth THIS book contains a complete summarybedplatecastingspriortomountingthe to Bristol, with the ocean mails for London. of Highland locomotives and includesmachinery.Thefinishedmachine is a 4 In speaking of railway museums; I am not,detailed information of every locomotive whichRapier concrete mixer ofcub. yd. capacity. March, 1948 NEWNES PRACTICAL MECHANICS 211 glass wool or other suitable material. Can youby Sir Isaac Pitman and Sons, Ltd., Parker Street suggest an alternative ?-D. Whrd (Derby). Kingsway, London, W.C. YOURscheme for sound -insulating your wallis Having read through some books such as the abov-e, quite good.You may use a sheet of asbestosyou will be in a better position to appreciate and assess composition or one of plasterboard, but, preferably, the problems of simple plaster moulding. QUERIES not one of metal.The sheet should sound " dead " It is, of course, quite impossible for us, within the when struck with the knuckles.Allow an inch or anspace of a short reply, to give you detailed instructions inchand ahalf spacebetweenthesheetand as to how to go about the task of casting for toy -making, the wall.This should be loosely packed with anybut, in brief, you should use ordinary plaster of Paris clean, fibrous material, such ashair,fibre,kapok, andcastitin smooth wooden moulds.Gelatine ENQUIRIES dried seaweed or fibreglass. moulds can also be used, but these are apt to be messy Fibreglass is. excellent stuff for the purpose.Itand difficult to work.The interior of the moulds may be obtained from Fibreglass, Ltd., Ravenhead,should be lubricated with a paste of soap, water and St. Helens, Lancs. glycerine in order to prevent the cast frorft sticking. Sterilised hair is also very effective. This is supplied You may add a little natural chalk (finely ground) A stampedaddressedenvelope,threepenny by Messrs. Edward Wenn and Sons (Worcester), Ltd.,to the plaster composition, but too much of it will stamps, and the query coupon from the current Worcester; Messrs.AngusBrothers,Ltd.,73, upset the hardening of the plaster.Also, you may add issue, which appears on page 48 (THE CYCLIST), Robertson Street, Glasgow, C.2. dry mineral colours in order to tint the casts.It is a must be enclosed with every letter containing a Whatever material you may use do not pack it toogood plan to incorporate with a plaster a little very query.Every query and drawing which is sent tightly. The whole idea is to break up the air existing finely ground asbestos powder with the plaster material, must bear the name and address of the reader. between the wall and the outer sheet into individualsince this, being fibrous, gives strength to the casts. Send your queries to the Editor, PRACTICAL " air cells " across which the transmission of soundAsbestos powder may be obtained fairly cheaply from MECHANICS, Geo. Newnes, Ltd., Tower House, becomes very difficult. Turner Brothers Asbestos Co., Ltd., Rochdale, Lancs. Southampton Street, Strand, London, W.C.2. The hardened casts may be painted directly.It is better, however, to brush them over with a solution Hand Printing on Silk of gelatine in warm water (say, 7 parts of gelatine in 93 please give me the formula andparts of water).This sizes the material, imparts a Emulsified Wax :Peroxide Dentifrice WILLprocess you for fast dyeing patterns on silk bylittle extra strength to it and keeps the paint on the T HAVE a recipe for making a hairdressinghand -the result to be washable ? surface so that it is not absorbed by the cast. preparation and one of the ingredientsis Can you also state where the materials (apart emulsified wax.I would be obliged if you wouldfromthesilk)areobtainable ?-M. Bishop" De -frosting"inRefrigerator :Water inform me how to make this emulsified wax.I (Kenton). assume that the wax to be emulsified is paraffinWE are afraid that to comply with your request for Hammer wax. formula., and methods for the hand printing ofT SHALL be glad of your advice on the following Also,couldyouinform me howI cansilk would necessitate the writing of a small treatise on points : make a tooth -cleaning peroxide dentifrice ?-the subject!This we cannot do, and we can only, (a) Isit practicable to employ a hygroscopic R. W. Hall (Chessington). in this connection, refer you for your adequate informa- chemical in a gas -operated refrigerator with a WE are inclined to think that the wax which yoution to any textbook on fabric printing, of which youview to diminishing the need forde -frosting " ? mention should be " white wax," which is notshould find many in your nearest reference library. If so, what chemical could safely be employed ? paraffin wax.However, an emulsion of any of these Silk is usually dyed with aniline dyes of the " basic " (2) Is it possible to abolish a persistent " water waxes is produced in the following manner : or " acid " class, such as fast acid scarlet, acid yellow, hammer " effect (evidenced by a loud ticking Nine parts of stearic acid and 30o parts of water, primuline,orangeII,brilliantgreen,naphthalenenoise) occurring in the main hard -waterfeed together with 3.5 parts of triethanolamine are mixedblack, methylene blue, methyl violet, etc.The funda-pipetoa mains -typewatersoftener ?The together and heated to boiling point (too deg. C.).mental method of printing comprises the making ofsoftener is installed. at the top of the house, and The mixture is allowed to simmer very gently.Eighty- very strong solutions of these dyes and in thickeningthe outflow is directly into the cold -water cistern. eight parts of the wait are melted separately and the them up by the incorporation of a soluble gum such as-V. T. Baxter (Bristol). molten wax is slowly added to the simmering solution,dextrine or British gum.In this way, a smooth dye the latter being well stirred continuously (preferably paste is obtained.This is rubbed evenly on the hand \ It is definitely not practicable to use a hygroscopic mechanically) until all the wax has been added. At block which is then applied to the silken fabric. The i)substance in order to diminish the need for de- this stage a creamy emulsion will have been formed.fabric is then heated in an atmosphere of steam for frosting a gas -operated refrigerator, the reasons being (a) Stirring is continued until the liquid has cooled downabout an hour in order that the dye may penetratethat all such chemicals are relatively expensive, and to normal temperatures. the fibres of the material and fix itself therein. (b) that the water -holding powers are strictly limited The emulsion thus formed is stable, and it can be The process of silk printing is not easy.It needs and that, in consequence, they would need constant diluted to some extent by the very cautious and slowmuch skill and experiment. and frequent renewal. addition of water. Materials mentioned above may be obtained from (2) The hammer effect which you mention may be You can make a " peroxide " dentifrice by addingany laboratory supply firm, such as Messrs. Vicsonsdue to the presence of one or more air -locks, but it to the ordinary dentrifice ingredients (chalk, magnesiumand Co., 148, Pinner Road, Harrow, Middx., or Messrs. seems more likely to be associated with carbonate, soap, etc.) about to per cent, of either sodiumGriffen and Tatlock, Ltd., Kemble Street, Kingsway,the main feed pipe, the water thus having to force London, W.C.2, but before you obtain them we wouldits way into the softener system against some undue percarbonateorsodiumperborate,preferablythe pressure.Inthisinstance,a personal examination former,which may be obtained from Messrs.B. advise a thorough study of a textbook on the subjectof the apparatus is more or less necessary before an Laporte, Ltd., Luton, Beds., or Messrs. Vicsons andof silk dyeing and/or printing, since this is a subjectaccurate opinion can be given, although we think that Co.,148,PinnerRoad,Harrow,Middx. The which cannot be worked merely from a " formula."if you examine the main feed pipe at or aboutits percarbonate should constitute about no per cent. ofProbably a suitable book for your needs would be: junction with the softener system you will find the the total weight of the dry dentifrice. A. Ganswindt (trans. by C. Salter): "Dyeing Silk,trouble to lie in some encrustation or blockage of the Mixed Silk Fabrics and Artificial Silks" (pre-war netcircuit at this point. Removing Scale from a Geyser price, 12s. 6d.). T HAVE an electrid geyser which scales up badly,Plaster Moulding Disinfectant Solution zdue to the hardness of our water.Can you T AM interested in making small toys and simple COULD you please give me some furmul= tell me of any compound or chemical which can for disinfectant, of which creosoteisan be used to dissolve the scale ? table decorations in animal shapes, cast iningredient,- and which can be produced cheaply ? The geyser has three coil elements immersedplaster of Paris, or a similar material.WouldAlso, could you tell me how to make a liquid in the water, and the lime forms a solid core,the moulds have to be carved in wood, each halfwith a strong pine odour for use in disinfectants ? which seems to expand, causing the wires toseparately, and then the plaster paste be squeezedWhere can materials for the above solutions be break. -E. G. Ingleby (Bristol). into the mould, or could a pattern be made fromobtained ?-G. D. Pauline (Rotherham). TF you place, at intervals of a week, about a saltspoonful which to make the moulds ?Also, can you refer me to a book on the subject ?Would the finished is of sodium metaphosphate inthewater -supply ORDINARY cresosote itself quite an effective tank of your geyser the scaling trouble will gradually cast have to be treated with varnish before paint- disinfectant when mixed with water, and in this belessened,the sodium metaphosphategradually ing ?-R. C. Evans (Hove). form aloneitisusefulfor" rough "disinfectant dissolving away existingscaleandpreventing theYOUR best plan to facilitate your proposed decora- purposes, such as the flushing of drains.Creosote is formation of additional scale. tive moulding and casting work istoprocurenever a constituent of the " finer " disinfectants. For Perhaps, however, you would be better advised toseveral books on the subject from your local librarythe better disinfectants of the Lysol type, the following consult Messrs. Albright and Wilson,Ltd., Waterand to read these up carefully.Interesting books foris a good formula :- Treatment Department, 49, Park Lane, London, W.r, you are :- Cresylic acid too parts (by weight) who manufacture a special and slowly -soluble form of S.W.Anthonias :" PotteryandModelling " ; Linseed oil (raw) .. 56 sodium metaphosphate to which they give the nameCatherine Peach :" Modelling and Casting for Chil- Potassium hydroxide " Micromet.' This hasbeenspeciallyintroduceddren " (Dryad leaflet) ; " Modelling with Self -setting (caustic potash).. .. for small-scale water treatment such as yours, and Clay " (Dryad leaflet) ; G. J. Cox : " Pottery for Artists, Water we think you will find it very well adapted for your Craftsmen and Teachers " ;H. and D. K. Wren : Dissolve the caustic potash in a little of the water purpose. It is, of course, understood that the phosphate - " Pottery : Finger -built Methods." and keep it separate from the rest of the ingredients, treated water will not be used for drinking purposes. One or two similar volumes are also published to -day which are all mixed together and heated over a water- Soap Substitute T WOULD be much obliged if you could give me THE P.M. LIST OF BLUEPRINTS a formula for a soap substitute, liquid or hard. -H. Haunch (Liverpool). "PRACTICAL MECHANICS" 12 FT. ALL -WOOD CANOE.* New Series. No.I.3s. 6d. TT would be quite impossible for you to make a soap "PRACTICAL MECHANICS" 10 -WATT MOTOR.New Series.*No.2. 3s.6d.

substitute for yourself since a long and complex "PRACTICAL MECHANICS" COMPRESSED -AIR MODEL AERO ENGINE.* New Series. chemical process would be involved. No. 3. 5s. There is an excellent soap substitute on the market "PRACTICAL MECHANICS" " SPORTS " PEDAL CAR.* NewSeries. No. 4. Is. called " Teepol." This can be had in liquid or in solid F. J. CAMM'S FLASH STEAM PLANT. New Series.No. 5. 5s. form from Shell Chemicals, ltd., 112, Strand, London, " PRACTICAL MECHANICS " £20 CAR SUPER -DURATION BIPLANE* W.C.2.If you can procure some of this material (which (Designed by F.J. CAMM), Full-size blueprint, 2s. is made from petrol residues) you can dilute it with water 10s. 6d. perset of four sheets. The I-c.c. TWO-STROKE PETROL ENGINE* or mix the solid material with soda or make it into a Complete set, 7s. 6d. In fact, you " PRACTICAL MECHANICS" MASTER paste with water and china clay, etc. BATTERY CLOCK* STREAMLINED WAKEFIELD can use it in numerous ways, according to your exact MONOPLANE -3s. 6d. requirements.But it would be quite impossible to Blueprints (2 sheets). 3s. 6d. make this or any similar " soap substitute " from any "PRACTICAL MECHANICS" OUTBOARD LIGHTWEIGHTMODEL MONOPLANE " formula." SPEEDBOAT Full-size blueprint, 3s. 6d. 10s. 6d. per setof three sheets. P.M. TRAILER CARAVAN* A MODEL AUTOGIRO* Complete set,10s. 6d. Sound -insulated Walls Full-size blueprint, 2s. P.M. BATTERY SLAVE CLOCK*2s. WILL you please inform me if it is possible to Newmas, Ltd., TowerHouse. insulate the party walls of a house so as to L-1 Theabove blueprints areobtainable,post free,from Messrs. George make them practically sound -proof ? Southampton Street, Strand, W.C.2. I had in mind the fixing of plastic or aluminium An * denotes that constructional details are available, free, with the blueprint. = sheet with a backing of, say,'in. thickness of Ti 212 NEWNES PRACTICAL MECHANICS March, 1948 bath.The caustic potash solution is then graduallymercury increases its regular rate of expansion.Since Freezing Mixtures stirred in and the heating continued for about an hour. mercury boils at 357 deg. C., it obviously cannot be An amber -coloured liquidwillresult.Thisisthe used for measuring temperatures up to2,000deg. C. T HAVE recently purchased an ice box, and wish finished disinfectant.For use it is mixed with a [large Some chemical thermometers contain mercury and to know if there is a composition of chemicals volume of water in the manner of Lysol. nitrogen.This gas makes it possible to use the mercurythat could be used for cooling purposes in place In the above formula the cheaper caustic soda can be expansion up to a temperature of 36o deg. C. of ice.-L. Clee (Southend). substitutedforcausticpotash, butitssaponifying Mercury freezesat minus 38.8 deg. C.From aTHERE is no chemical or chemical composition action on the linseed oil is not so potent. few degrees above this temperature to a few degrees which is economically practical as a replacement The liquids having a strong pine odour which youbelow its boiling point the expansion of mercury is for ice in a cooling box.Solidified carbon dioxide gas desire if pine oil or pine essence, both of which are veryregular, this constituting its thermometric range. may be used,but thisisexpensiveanddifficult scarce, owing to the reduction of imports.You will (2) So long as the elements of a thermo-couple areto obtain at the present time.The various chemical probably be able to obtain pine essence from Messrs.united in firm contact at one end so as not to set up freezingmixtures may betried. They arequite John Beard and Son,Ltd., Great AncoatsStreet, urdue resistance the actual expanse of the contacting efficienton asmallscale, but theyare hopelessly Manchester, priceabout 5s.perlb.Theotherarea does not affect the current.The current is mainlyexpensive and short -lasting on the larger scale. materials above mentioned can be obtained from theinfluenced by the dissimilarity of the metals and by the Formula' of some of these mixtures are same firm, or from any firm of painters' suppliers. temperaturedifferencebetweentheheatedand given below : unheated ends of the couple. Potassium nitrate The thickness of the wire from the couple does' ot Ammonium chloride(sal am- Methylamine Hydrochloride influence the current generated. moniac) . 21b. T SHALI. be glad if you will please inform me Water .. ..5 pints -1 how to prepare methylamine hydrochloride (CH3NH3CI) from ammonia or itssalts, andView -finder for Folding Camera Potassium nitrate 21.1b. hydrochloric acid.-A. Healey (Hemsworth). THAVE a". Zeiss -Ikon " folding camera, for Ammonium chloride.. 2!.1b. Mlk ETHYLA MINE is not readily made directly from 1 whichI wish to make a direct -vision view- Sodium sulphate 41b. v ammonia, although it is obtained in small quantity finder, folding type, to be fitted on the side of Water .. 9 pints byheatingmetholalcoholwithammoniacalzinc the body. chloride. The camera takes size 27 film (eight exposures, Sodium sulphate 8 parts (by weight) It is best made on the laboratory scale from acetamide, x 2!,in.), and isfitted with a Trinastigmat Dilute hydrochloric acid (s in 4)5 parts which latter compound is made by slowly distillinglens,f6.8. Theprincipaldimensions,with solid ammonium acetate (see any text -book of practicalbellows extended, are given in the accompanying Ammonium nitrate .. .. 41b. organic chemistry for details of this acetamide pre-sketch. Water ...... 4 pints paration). Itisintended that the view -finder shall be Strong cooling by any of these mixtures would last The acetamide is treated at ordinary temperaturesfitted in the area A, and take the form shown five or six hours at the most. with bromine.It thereby forms colourless crystals ofin the smaller diagram. All the above materials can usually be obtained from acetobromamide. A cold dilute solution of caustic Can you please inform me of the size of viewing any drug store.Some paint dealers supply them, also, potash is added to the .pcetobromamide. A yellow orifices required and their dimensional relation- as well as horticultural merchants. solution results.This is'gentiv warmed.It evolves aship with each other ?Also any practical hints mixture of carbon dioxide gas and methylamine, whichto assistin the execution of the lob ?-G. G. latter is a fishy -smelling gas, extremely soluble in water. Fowler (Luqa, Malta). Illuminated Signs The methylamine gas is led into dilute hydrochloric CAN you please help me with the following. acid (one in four). The resulting solution of methylamineTOUR proposed direct view -finder isquite sound problems ? hydrochlorideissubsequently concentratedforthe in design, and it will be satisfactory in practice, Prior to the war certain shops had showcards recovery of the solid hydrochloride. always provided that it is accurately made and carefully in the window which were " illuminated " by a fixedand aligned to the side of the camera.This violet bulb, causing the lettering on the cards to type of view -finder can be purchased from a goodappear luminous. Tattooing " Inks" What is the scientific principle underlying this COULD you please state the constituents of Existing Viewfinder idea ? tattooinginks, and where they may be Dimension Of Upper What is the type of bulb used and source of obtained ?-P. D. Mallocch (Perth). supply ? TATTOOING inks are not really inks at all.They Wfndow 25 x :375" What arc the substances with which the pig- are merely insoluble pigments ground up with ment is impregnated ?-J. Williams (Denton). a little water or water and glycerine, the resulting fine colour -paste being inserted in the tiny punctures CERTAIN materials which are more or less white underordinaryilluminationfluorescevividly made by the tattooing needle. under ultra -violet rays.Salicylic acid, quinine sulphate, Any pigment may be used provided that it is non- zinc silicate, cadmium tungstate, calcium tungstate, poisonous.Pigments which have been employed are: potassium, bichromate,zincsulphideandvarious lampblack, indigo, red iron oxides and even green organic compounds all give fluorescent responses under chromium oxide.We understand that such " inks " U.V. illumination.Hence, when a design is prepared are not now commercially manufactured.Your best with an ink or paint containing one or other of the plan, therefore, isto purchase a few tubes of good materials and is illuminated with U.V. rays, the design water-colour paints fromareputable firm, such as Messrs. Windsor and Newton, Ltd., of London, and becomes seeminglyself -luminous.These materials 5375 may be ground toapowder, and mixed topaint to use these for your experiments. consistency with a clear cullulose or oil varnish. Animals, of course, may be tattooed by means of a You should be able to obtain the necessary varnish silver or magenta marking ink, but the employment of medium fairly locally from Messrs. James Beard, Ltd., such inks on a human being is unsafe. t6,GreatAncoatsStreet,Manchester,andthe fluorescent materials from Messrs. J. W. Tcwers and Dye for Celluloid Co.,Ltd.,44,ChapelStreet,Salford,3. T AM interested in making one or two sheets The electric bulb necessary is one emitting some Iof clear transparent celluloid, which I require type of U.V. illumination.We understand thatall in order to carry out some experiments in the small and portable bulbs of this type are no longer field of cartoon tine projection. manufactured, for which reason we can only refer you The size of sheets required would be about Lens to a large firm of electrical wholesalers,such as the 12in. by zoin.Could you please give me a list of Trinastigmat Wholesale Fittings Co., Ltd., Shudehill, Manchester, the ingredients to be used in making the sheets ? , 6.8 F= cm. or,perhapsbetterstill,totheGeneralElectric Could you also tell me if any special paints or Company, Ltd., Wembley, Middlesex, or to one or dyes are needed in order to paint on celluloid ? other of their agents. If so, could you supply me with the formula for It should also be noted that uranium glass gives a making these ?The colours I should need are greenish -yellow fluorescence under U.V. illumination. red, black and yellow.-G. Sawyer (Bury St. Signs may be made out of this material which you Edmunds). 4-125" might possibly be able to obtain from Messrs. Chance TT is impossible for any unskilled individual to make Brothers, Ltd., Oldbury, Birmingham. A celluloid sheets for himself of the size you mention, or, indeed, for that matter, to make celluloid atall in a satisfactory condition.Celluloid is essentially a Episcope Lenses plasticised compound of gun -cotton and camphor. COULD you please advise me on the arrange- The details of its manufacture are maintained more ment of the lenses in an episcope ? or less secret.The best you can do in the present At present I have one double convex lens, 21in. circumstances is to obtain a good book dealing with diameter, t5in. focal length, in the instrument celluloid and to study itcarefully.You will then Proposed Viewfinder I am building, but it does not project a fully clear be in a position to appreciate the intricacies of the Fitted At:4' image on the screen.When the centre of the process. A bookwhich we canrecommendis image is in focus the remainder is blurred. F. Bockmann (translated by Stocks) :" Celluloid : Side view of d folding camera and I should be very pleased if you would prescribe Its Raw Material, Manufacture, Properties and Uses." a suitable lens construction about 3Lqn. diameter, This was published (pre-war) at 8s. 6d. net. detail of collapsible view finder. giving the type of lenses used and the order, also To make a stain or dye for celluloid, dissolve clear where I couldbuy them.-G.W.Johnson scrap celluloid in a mixture of about equal parts ofphotographic dealer, such as Messrs. Jonathan Fallow - (Stapleford). acetone and amyl acetate.Then make up a strongfield, Ltd., Newman Street, London, W., or Messrs. THE actual diameter of a projection lens or objective solution of a dye in methylated spirit.Add a little ofWallace Heaton, Ltd., Bond Street, London, W.I. has nothing to do withitssuitability for the this to the celluloid solution, but not too much of it. If you wish to make one for yourself the rear aperture purpose. A good stain will result. should measuretin. x in.andthefrontaperture In the case which you mention the trouble is due zit 6in., the apertures being t /in. apart.Theseto your using an insufficiently corrected lens, the lens figures are approximate only, and are correct only whenin question not being capable of focusing the whole Expansion of Illercury :Thermo -couple the camera is used for distances greater than aboutof the image at the one time. WOULD be obliged if you could supply the 6ft.You should make a " hook-up-" of the finder first What you require is not a single lens, but a combina- answers to the following : of all, and then test it out photographically on a well-tion of two lenses fixed at about equal distances from (a) Over what range of temperatures does defined object before finally finishing -off the device. acentral aperture or" stop."This, the so-called mercury continue to expand, i.e. when, does it Alternatively, you could have in place of the rear " doublet "lens, forms thebasis of allprojection stop rising ?Would it be possible to use mercury aperture a small rectangular reducing lens.A front lenses, and also of photographic portrait lenses. Either of to measure temperatures up to, say, 2,00o deg. C. ?aperture would not then be needed, its place being takenthese lens types will suffice for your purpose, but the (2) How isthe output ofathereto -couple by a small metal upright carrying a small disc, theorthodox projection lens will be.the more satisfactory of affected by the amount of dissimilar metals incentre of which is exactly coincident with the centre ofthe two, and it will give you a perfectly focused picture. contact, i.e. how would the output of a couplethe reducing mirror and fixedtin.or in.distantYou should apply for secondhandliststoMessrs. welded together at the tips compare to the output from it.This type of finder can also be purchased. Broadhurst, Clarkson and Co., Ltd., Farringdon Road, of a couple welded together for, say, 2in. ? Thedeviceissimplycutoutinlightmetal London, E.C.4,ortoanywell -establishedphoto- Also, what is the effect of using different gauges (aluminium), whichisafterwardsblackened.Both graphicdealer,as,forexample, Messrs. Wallace of wire for the couple ?-W. H. Beran (Brighton).aperture frames should be made so as to fold inwards, Heaton, Ltd., New Bond Street, London, W.I. MERCURY expands progressively until it reaches the larger one over the smaller one, so as to give com- You should note that a 15in. focal length lens is not (I)a temperature near its boiling point.At this pactness to the device.Cross wires or lines should be necessary. A lens of Bin. focal length (or thereabouts) temperature (a few degrees below itsboiling point)provided with either design. will be quite sufficient. March, 1948 NEWNES PRACTICAL MECHANICS 213 Same InterestingOffersby RIGHT MODEL ENGINEERS FOR THE TURNER : ELECTRADIX IN DYNAMOS. 12 volt 10 amp. D.C. shunt Lathes,3,and4',S.S. BenchMillers.Drilling Machines. wound 1,400 r.p.m., C.A.V. in new condi- Hand Bench Shaping Machines. tion,£411010. 30v.5 amp.1,500r.p.m., THEORY £51010.50170volt10 amp.1,000r.p.m., FOR THE WOODWORKER : £141010. 24 volt10 amp 80011,000 r.p.m., 1010/0. centres.4in. Planers. Saw Wood Turning Lathes, 21' and 5+" METERS.IIC Voltmeters,4in.,G.E.C. Benches. Sanders. Spindle Moulders. 0-60volts,451-; Ammeters tomatch, 0-40 amps., 451-. Electrostatic voltmeters, ., meowsilWifr fit e Pedestal Jig and Fret Saws. panel type, 3,500 volts, £31010. SMALL MOTOR GENERATORS, by Theoretical Knowledge and Practical Perspex -All sizes and coloursinstock. E.D.C.6v.input 230v.D.C. 40 m.a. Knowledge you must have if you are output, take the place of H.T. batteries ; to "snake the grade" as a qualified in new condition, 551-. technician. Through the medium of NUTTALL'S (LATHES) LIMITED, INDUCTOR ALTERNATORS. 230 special postal courses,the Pitman volts 2 amps., totally enclosed, single or College of Technology can provide MANSFIELD, NOTTS. 3 -phase ball bearings, 2,800 r.p.m., 4 -pole you with the right theoretical training type,£811010,needseparateexcitation, ELECTR IC ENGRAVERS. -Powerful 618 volts 618 amps. which will not only materially assist Remote Contactor.New, with many instrumentsincylindricalcase,on your progress on the practical side, but useful items including luminous dial stand withspring attachment and METAL RECTIFIERS. Large plate type. and pointer, 3 amp. toggle switch, two switch.Suitable for dog collars, tool 75 volts 6 amps, £411010. 12 volts 15 amp. will enable you to qualify more easily relay bobbins wound 3 ozs. clean enam- 4-6 volt model, price 3 parallel bridges, 501-. for a well -paid technical post when elled copper x 36g. wire, two Platinum marking, etc., contacts, cable leads,etc. 311 each. 50/-; A.C. Mains model. 20()-240 volts, TRANSFORMERS. B.T.H. 20012301250 v. your apprenticeship is completed. 60/- ; A.C. Engraver only 50,-. 3 different Multi -point Switches, silver TELEPHONE SETS,comprising 2 input 2 volts 20 amps. and 75 volts 6 amps. contacts.3 for 2/-, 7/6 doz. G.P.O. hand phones, 2 bells. 2 pushes with15taps,701-. Elementary Single Subject 10 -way Terminal block and connector. and 80ft. twin wire.Price 65/-, post Engineering Course: -Courses include: - 30 screws, V- each,6 for 5'-. SWITCHES. free. Singleinstrument.25/6. Dewar key panel Workshop CalculationsWirelessEngineering Harnofll heat -resisting rubber covered 6 inch Brass Brackets lin. thread, 1/9. copper connecting wire. 12yds.2/-. S.B.C. Fancy glass shades 1'9. Circular type, 8 -pole C.O. Workshop Training Motor Engineering Peribraid sleeving, finest quality, high resistances on china base 10 ohm_ 2/-. flush fitting, SI-. Engineering Science Diesel Engines voltage, various colours, 1rn.m.,1.5 Screwplates for threading 0 2 4 B.A. 4/6. Yaxley 3 -pole Plastics rn.m. 4d. yard. MOTOR. -4-6v.dry batterydriven, (Mechanical & Electrical) Bakelite bobbin wound Itozs. clean well made, powerful, 11/6.Illustrated 3 -way,316 ; 8 - Engineering Drawing RadisCommunication usable 36 s.w.g. enamelled copper wire. list,6d. CarbonDiaphragm pole1 -way,316.D.P.C.O. toggle switch 10/6 dozen. 250 v.I amp., flush panel,31-. S.P.C.O.,21-. Mechanics Elements of 1/- each, 1/- each and carbon granules 641. packet. Structural Used ex-R.A.F. low resistance earphone BATTERY CHARGERS FOR A.C. 8 -way Lucas switchbox,316 ;6 -way,31-. General Science with switch. 2/6. MAINS. FOR CHARGING 2 -volt accu- Engineering ex -Army high Electricity&Magnetiam New S.D. Brown mulators at I amp. Parts with diagram. RESISTANCES. Var.slide vit. enamelled Elements of Quantity resistance headphones, complete with 12/6.Complete 21/8: Postage 10d. tube with laminated brush and slides,14 Heat, Light & Sound Surveying headband and leads.12/6 perpair. FOR TRICKLE CHARGING CAR ohms 5amps.,suitable with50170 New U.S.A.singlesmallearphone. CELLS, parts with diagram.Output volt Write at once Jar free prospectus to: 1,000 ohms resistance.56. 11 amps. for 6v. cells.30/- s.t.For dynamo for charging circuits at 5 amps., New U.S.A. high resistance headphones. 12v.cells, 35/-set. 251-each. Asnew. complete with headband and lead. 1211 Larger sizes quoted for. TELEPHONESforHouseorOffice. per pair. MINIATURE HEAD- As above, but special lightweight with PHONE. Reproduces Constructors' Parts for your own set-up. PITMAN detachable rubber ear guards. Com- equal to best 'phones. Ex G.P.O. stocks,wall type, comprising plete. 15/- per pair. Fits into ear, does not Bracket Mike, Transformer and Condenser, COLLEGE OF TECHNOLOGY. All above postage extra. require headband. Two Magneto Bell in walnut cabinet, 8in. x 6in. Send S.A.E. for list of insulated copper nipples large and small x 3in.,fittedterminals and connections, 177 SOUTHAMPTON ROW, W.C. I wires, screws, nuts, tags, Ebonite and 10 ohm or 1,000 ohm. Switch Hook and Contacts, Hand Magneto laminated Bakelite panels, coil formers, Blackorfleshen- Generator and G.P.O. Receiver, 351- per Principal: H. R. Light ,B.Sc.(Lond.),F.C.I.S. etc., etc. aprnrieclele3d0.,.. 4ft. cord. pair,with wiring diagram. POST RADIO SUPPLIES ECONOMIC ELECTRIC CO., G.P.O. Sound Powered hand combination 33 Bourne Gardens,London, E.4 64, LondonRoad,Twickenham, Telephone, in moulded bakelite case, switch Middlesex. To/.: POPesgrove 1318 in hand, cord and plug, new,211-each. ELECTRIC. MOTORS CRYSTAL SETS.The 24v. D.C. for driving models of all new Lesdix Boudoir Set, descriptions,and cameras.Canbe TOY -CASTING MOULDS bakelitecase, condenser adapted for many ,useful experimental tuning, semi -perm de- Purposes.All brand new. Price1.5' - tector, 1716.H.R.Head- each. --- DEEP CUT phones with headband and FUL-VUE SAFETY SPECTACLE cord,151-. American -typesteelframe.plastic Soldiers,sailors,airmen,ships, fore bridge, unbreakable lenses, natural 'planes, tanks, cars, farm animals, MICROPHONES. Hand vision.Ideal for people whose work mikes in moulded bakelite involves danger to the eyes through Citing moulds deep wild animals and keepers. Sample casefittedlatestpattern dust, heat and flying particles.The soBattledress mould 3,6.Plastercraft Metal G.P.O. Inset, 4)6, post 6d. frame is of a quality and design un- ldiers. Aeroplanes, Tannoy hand mike (as obtainable in this country ;it can be Formsand Wild Moulds. -Wall plaques,galleons, illustration), Multi -cell car- worn to great advantage in comfort Animals.Cars.etc. and appearahce.10/- Stamped envelcpe brooches,dogornaments,etc. bon type, metal case with rotlist. Illustrated neat switchinhandle for POCKET SAW rki Catalogue 6d Samplemouldofbrooch3 6. sportsmeetingsandan- Of high speed steel.When extended nouncers, 1216. 42ins. long. Complete'with sharpening Germanflatmoulds from3 6. Specia Me and tooth bender. Price 10/- each. Transformer, 816. G.P.O. S.A.E. for List.6d. for Illustrated mikebutton, I in. dia., ORDNANCE MAP CASE Catalogue. filled carbon granules and Celluloid window 20ins. x tains.Zip - fitted mica diaphragm, 316 fastening. laminated cloth roll, 20 -. NUTHALL, 63, ST. MARK'S RD.. each.S. G. Brown midget SPRING BALANCE WEIGHER HANWELL, LONDON,W.7 microphonebutton, 101 - Pocket type,weighs up to12lbs. each.High Ratiomike Marked off in 1lb. sections.Overall transformer,416. G.P.O. MikeInsets. size 31ins.7/6 each. MAKE MONEY IN 216 each. No C.O.D.Delivery 8 to 10 days:Full THE HANDYMAN'S METAL BOXES 9in. x 9in. x 8in., with money back guarantee. lid and front fasteners ; loops for carrying YOUR WORKSHOP " Odds and Ends" strap and plinth for panel,1216.. M. LAWTON (Dept. P.M.), SETS of CLEAR CONSTRUCTIONAL SPEEDMETERS, by A.T.Speedometer 121-123, Bury New Road, DIAGRAMS andinstructionsfor MIXTURE Co. 1,500 r.p.m., 4in.blade,dial with BUILDING YOUR OWN white scale and figures, 201-. Manchester, 8. (I) TOY, MODELor WOOD- Here's a useful assortment of about WORKER'S LATIS,E,3/6. 21b. components for mechanics, SEND -RECEIVE HandCorns. All - (2) Power or foot treadle drive FRET modelmakers,etc.Screws,nuts, metal field Hand Coms. for portable or era: JIG SAW MACHINE, 3/6. washers,grubscrews,taperpins fixed stations.The famous No. 16 Govt. THE WORLD'S GREATEST BOOKSHOP (3) Ball hearing Table Model CIRCU- pivots, nipples, studs and innumer- type, used in field telephones; mike and LAR. SAW, 3/6. able small machined parts.All high earpiece with damaged finger switch easily (or 9i- for the three.) quality surplus from production runs. repaired, 51-. (No. cords supplied.) ALL these well tested; simple machines lotsalike. FOR.. BOOKS 666.-, can be built EASILY from READILY No rejects and no two MULTIPLE CONNECTION STRIPS New and secondhand Books on every subject OBTAINABLE PARTS A N D 7s.6d.,post free. of soldering tags ; Telephone type, moulded WEBUY BOOKS, TOO MATERIALS ONLY and will turn out mounting, 60 -way, 316.R.A.F.10 -way tele- 101 Saleable articles for the shops and SPENCER COMPONENTS phone terminal strips, 219. 119-125, CHARING CROSS ROAD, market.Prompt posting. LONDON, W.C.2. 22 CAROLINE STREET POLE STRAY STRAINERS foraerial Gerrard 5660 (16 lines). Open 9.6 (inc. Sat.) P. H. BARHAM, Bridge Avenue. masts,transmittingand television, 116 St. Sampsons, Guernsey, C.1. BIRMINGHAM 3 each.Swan -neck Insulatorskitgutter fixing,116.

PARCELS. 71b.useful oddments for the NICKEL PLATING ADANA PRINTING MACHINES junkbox.All clean,dismantledfrom RATCHET & REVOLUTION Print in the odd hours with an Government and other surplus apparatus, Complete Equipment, Including. Nickel Adana -still the most absorbing Anode, Plating Salt, etc. Full instruc- of crafts. No.1 II/S 716 post free.(Not for Overseas buyers.) COUNTERS tionsforPlatingOrnaments,Car Machine24.10.0. Askfor r'`' 7;7; ,j7.1.3.., Fittings, and all Metal Parts.Flash - No. 2WS Machine Please includepostagefor mail orders.

I lamp battery only required. 69.15.0.Will pay Leaflet No. for itself in a month or Speed upto Price 151-. post free. two. Sendforillus- ELECTRADIX RADIO 0,000 r.p.m. 1101.80ROW & CO., trated foldertoDept. 214, Queenstown Road, London, S.W.8 71, Weymouth Bay Avenue, P.M. 10, B. & F. CARTER Weymouth. Adana (Printing Machines), Ltd.. (Late Queens Road) &Co, Ltd., Bolton5 15/18, Church St., Twickenham, Middx. .iii-Telephone :MACaulay 2159 214 NEWNES PRACTICAL MECHANICS March, 1948

GALPINS 111111111Me ELECTRICAL STORES 408, HIGH STREET, LEWISHAM, LONDON, S.E.I3 BARGAINS Phone :LEE GREEN 0309 LEARN TERMS : CASH WITH ORDER (NO in Ex -Government C.O.D.) EX -GOVT. (GEC) ELECTRIC FANS, Stocks 12 volts AGOG laminated field, complete TRIPODS, aft.high when with Sin. impellor. New boxed, 251- each, TO erected. Fitted truss thread II-post. Transformer tosuit 230 volts and cap, web sling for carry- ing. Inwoodormetal. input 10116 volts at 4 amps. output, 3216 Suitable for Surveyors, pro- each. jectors, cameras, din-1 A/6 MAINS VARIABLE RESISTANCES. playpurposes,ete. Ex -Govt. (new) slider type, 450 ohms to The famous "WALKIE carry 0.7 amps., 301- each ; 4,000 ohms, EARN TALKIE" Aerial. Spring .25 amps., 351- each. Worm wheel control Brass. Extends 8'3' 14/6 from 151". slider type, 60 to carry 11 amps., 2716 each ; 5.7 ohms 8 amps., 3216 each. Dimmer switch armtype 2,700 PRESSURE 4 -VALVE resistancesstud Leave the overcrowded ranks GAUGE SUPERTIET ohms to carry .27 amps., 301- each. of the poorlypaid-let reads 0-150lbs. Receiver for short EX -GOVT. (NEW) MAINS TRANS- The Bennett College help you to the top where there is Fitted - good wavescomplete. FORMERS, 2001250 volts 50 cys. I ph. lengthofcop- Needs only bat- input 525101525 volts 150 Mlamps. 6.3v always plenty of room for the well -trained. Just choose per tubing. 1/6 teries & 'phones. 5 a., 5 v. 3 a. output standard rating, 351-, post 2I-.Mains Smoothing Chokes, 10 Hy. your career or let us advise you.The Bennett College PYROMETER 29/6 150 Mlamps. 180 ohms D.C. Resistance, 816 withits TYPETILER- Matched 'phones. each. Ditto, 100 Mlamps., 516 each, post 9d. proud traditionoffriendlypersonaltuition MOMKPER 9/-; H.T. Bs t- Smoothing Condensers (oilfilled), 4 M.F. and its long record of triumphs, is the most progressive, reads 0-100' 0 /C tery 9/-. Packing 1,000 volt working, 316 each.(All the above Centigrade WU & Insurance 2/6. can be offered in large quantities.)Please most successful Correspondence Collegein the World. PORTABLE ELEC- write for special quotation. We teach nearly all the Trades and Professions by post TRIC II E A T I.: It, EX-R.A.F. MICROPHONE TESTERS deal for lofts.37/6 (new). These consist of a FERRANTI 0 to allover theGlobe. DISTANCE MAKES NO 500 watts 450 Microarnp 21.in. scale meter shunted to DIFFERENCE. 1.MIAincorporated Westinghouse Recti- 3IULTIMETER. 17 ranges,AC/DC fier,the whole encasedinpolished teak volts, al/amps & ohms.New and je-1 case calibratedat present 0 to10 volts, perlect. X, 3216 each. * CHOOSE YOUR CAREER AND EX-R.A.F. POWER UNITS, TYPE 225 (new). Containingthefollowing com- ELECTREC ponents : 3-V.U.111 Rectifier Valves, WE WILL SEE YOU THROUGH PANEL 1-5U4G 2-EB 34s,3 -Multi Contact Relays, HEATERS. High Voltage Condensers, Chokes, Trans- Accountancy Examination; Mining, Electrical En -ineering Can be placed or Advertising and Sales Management Motor Engineering fixed anywhere, formers, etc.To clear, 651- each. Agriculture Municipal and County Engineers EX-R.A.F. ROTARY CONVERTORS, A.M.I. Fire E. Examination Naval Architecture soo watts 52/6 D.C. to A.G.,12 volts D.C. to 220 volts Applied Mechanics Novel Writing 50 cys. I ph. A.G. at 100 watts, 851- each. Auctioneers and Estate Age.,L, Plastics Ditto, Admiralty Pattern,110 volts D.C., Aviation (Engineering and Wireless) Play Writing Carriage Paid (Dept. it) Input 230 volts A.C. output at 200 watts. Banking Plumbing £1211010 each. CIF Ditto, 220 volts D.C, Blue Prints Police, Special Course Input, same output, £15, CIF. Another, Boilers Preceptors, College of INSTRUMENT CO., 24 volts D.C. Input, 50 or 100 volts 50 cys. Book-keeping,Accountancy and Press Tool Work k14 Harrow Rd., London, Wjd I ph. at 300 watts, £31151- each, CIF. Modern Business Methods Production Engineering EX-R.A.F. CRYSTAL CALIBRATORS E.Sc. (Eng.) Pumps and Pumping Machinery UNITS,Typel8 R.A.F. serial No.10a115237 Builders'Quantities Quantity Surveying-lns,.. of Quan- These units contain 100Kclsxstal2-EF Building, Architecture and Clerks tity Surveyors Exams. 50 valves and numerous other itemsall of Works Radio Service Engineering new and unused, 351- each. Cambridge SeniorSchool C -rti- Radio (Short Wave) LABORATORIES SPECIAL OFFER METERS, ALL NEW ficate Road Making and Maintenance BOXED. Moving Coil First -grade Instru- Carpentry and Joinery Salesmanship I.S.M.A. of allbranches o' industry are ments, 0 to 20 volts, 101- each, or 3 for 251- ; Chemistry Sanitation 0 to 40 volts,1216 each ; 0 to 10 amps., Civil Engineering School Attendance Officer equipped with the finest 151- each ;all 2in. scale.0 to 25 volts A.C. Civil Service Secretarial Examinations apparatus and chemicals obtain- calibrated 50 cys., 251- each ; 0 to 4 amps. All Commercial Subjects Sheet Metal Work able.We suggest you consul Thermo Coupled, 251- each ; 0 to 3,500 Commercial Art Shipbuilding volts Electrostatic, 351- each, all 21in. scale. Common Prelim. E.J.E.B. Shorthand (Pitman's) us for your requirements. MAINS TRAtiSFORMERS (AUTO Concrete and Structural Engineer- Short Story Writing WOUND). Voltage Changers tapped 10, ing Social WeTare 20, 25, 90, 130, 150, 190, 210 and 230 volts, Draughtsmanship, all Branches Speaking in Public Send 2d.fortotes, Student PriceLists allat1,000watts,a combination of 34 Engineering, all Branches, Subjects Structural Engineering and Order Form. voltages can be obtained from this Trans- and Examinations Surveying former, new ex -Govt. stock, £51101- each, General Education Teachers of Handicrafts " Easy HomeChemistry for Boys " carriage 51-.Mains Booster Transformer, G.P.O. Eng. Dept. Telecommunications 21- (post 4d.) tapped 0, 6,10, 19, 175, 200. 220, 225, 240, Heating and Ventilating (City and Guilds) and 250 volts at 1,500 watts (new ex -Govt.), Institute of Hous:ng Television £5151- each, carriage 5/-.Another, 200 volts Journalism Transport Inst. Examinations Electrotors (Electric Motor) input 240voltsoutputat2,500watts, Languages Viewers, Gaugers, Inspectors No. 240 ...816 (post 4d.) £71101-, carriage 716. Another, 2,to I ratio, Mathematics Weights and Measures Inspectors No. 242 ...1016 (post 4d.) 110 volts input 220 volts output or vice Matriculation Welding versa at 4,000 watts, £121101-, carriage 101-. Metallurgy Wireless Telegraphy and Telephony (All supplied with Pulley.) Another, 230 volts input tapped output Mining, All Subjects Works Managers ListsId. S.A.E. Trade enquiries invited. 40, 41, 42, 44, 46, 47, 49, and 52 volts at 100 amps., £15 each, carriage101- ; the If you do not see your own requirements above, write to us on latter two are double wound.Another any subject. Fullparticulars free. VICSONS & CO., auto. wound, tapped 0,110, ISO, 190, 210 Dept. " P. M.' and 230 volts at 1,500 watts, £61101- each, carriageSi-. Ditto, 2,000 watts,£7151-, carriage 51, COUPON. CUT THIS OUT 148, PINNER ROAD, EX -NAVAL CATHODE RAY RECTI- HARROW, MIDDLESEX FIER UNITS. These units are new and III III NM =I =I ME VII as a a =I al. =II a lin 12IIII OM ME ND NM MI 11111 IM a IIIII Consisting of high voltage weigh 90 lbs. IF To Dept. 76, THE BENNETT COLLEGE condensers,15 volume controls,chokes, YOU AT- approx. 100 resistances and condensers all TEND TO THIS LTD., SHEFFIELD coloured,codedormarked,valveand NOW IT MAY JUBILEE "" HOSEDRIVE CLIPS tube holders (no valves), transformers are MAKE A Please send me (free ofcharge) includedbut arefor 500 cys.,priceet. WONDERFUL The long -life clear, 4216 each, carriage paid. Particulars of (Cross outline clip with the MAINS TRANSFORMERS, EX -GOVT. DIFFERENCE whichdoes All 50 cys. input 230 volts input 500/0150C TO YOUR Your private advice not apply) ever -tight volt at 250 Mlamps. L.T.5v.3a.,3716, FUTURE. about grip carriage 3/6.Another 50 volts at 30 amps. TheBestKnown output, 751- each, carriage 61-.Another I PLEASE WRITEIN BLOCK LETTERS two L.T. windings, 61volts at10 amps., For Radiator Joints, 2716 each. Another 230 volts input 700 volts Name Air, Oil and at ISO Mlamps., 4 v. 2 a., 4 v. I a. output, 2716 each, carriage 316.Another 700101700 Water Ho; t Address Joints volts 80 m.a.,12 v. I a., 4 v. 2 a. output, 301- each. Wo guarantee a EX-R.A.F. IFF UNITS.As new, these Tight Joint units contain 10valveS.P.41s, Ef50s, EA 50s,etc., also approx. 100 resistances L. ROBINSON & Co. and condensers, also complete with motor 25, London generator,12 or 24 volts input 450 volts Chambers, at 50 Mlamps. output.To clear, 24 -volt The Co/lefewitha OSWellOSbPOINS GILLINGHAM, KENT type, 351-; 12 -volt type, 4216, carriage 3/6. March, 1948 NEWNESPRACTICAL MECHANICS 215 For the "far-seeing" cyclist The NEWPHILIDYNE RECD. TRADE MARK CYCLE DYNAMO LIGHTING SET (TYPE L')

TheNEW8 -Pole Dynamo (Type 7422) weighs only ounces yet is rated at 6 volts, .5 amps and provides good bright light even at walking pace.Particularly smooth action, free from pulley drag or " snatch ". Self-lubricat- ing.Polished aluminium finish. The NEW Headlamp is smart, streamlined and is de- signed to take fiat battery for parking and traffic halts. Switch for either battery or dynamo connection to both lamps is sited on top of lamp. Finished in black lacquer with chrome -plated rim and polished reflector. TheNEWRearlamp is a component part of the dynamo.Lens is of heavy plastic, unbreakable GOOD, in normal use, prismed internally with smooth USEFUL convex exterior. Polished aluminium finish. (Obtainable from the trade only). LIGHT even at walking speed PRICE complete with twin -flex cable and clips 4316. Demand is heavy, Made in Great Britain, a product of so place an PHILIPS ELECTRICAL LIMITED order NOW CENTURY HOUSE, SHAFTESBURY AVENUE, LONDON, W.C.2

BRANCHES AND SALES DEPOTS AT BIRMINGHAM, BLACKBURN, BRISTOL, CARDIFF, EDINBURGH, GLASGOW, LEEDS, LIVERPOOL, MANCHESTER, NEWCASTLE, NOTTINGHAM, SHEFFIELD. ish.at4P) A light grasp here FE RODO lined shoes ensure an instant velvet -smooth response to your hub brakes. means a suregrip here FERO BRAKE LIN - EN - LE -FRITH REGO TRADE MARK FERODO LIMITErD CHAPEL riFIER1000 A Member of th e rur ner & Ne w a11 Organization March, 1948 216 NEWNES PRACTICAL MECHANICS

DIAMOND JUBILEE 1888-1948 yr ea d 8E11315.

J.A.PHILLIPS & CO. LTD. BICYCLES SMETHWICK BIRMINGHAM March, 1948 THE CYCLIST 41 THE I* All letters should be addressed to theEditor," THE CYCLIST," George Newnes, Ltd., Tower House, Southampton Street, Strand, London, "s W.C.2. Editor :F.J. CAMM Phone : Temple Bar 4363 Telegrams : Newnes, Rand. London VOL. XVI MARCH, 1948 No. 312

Comments of the Month By F. J. C.

B.L.R.C.Policy THE B.L.R.C.ison the threshold ofsomethingillegal,orof which theyarecomfort to other road users and seriously becoming the accepted authority forashamed. Little wonder that the public knowsincrease the risk of road accidents. control of cycle racing in England,practically nothing about cycle sport, and that The report also recommends that head- notwithstanding the fierce attacks from thenewspapers ignore it, and only comment uponlamps and passlamps should be mounted not paid advocates of existing organisations, andcycling atall when something happens tohigher than 3ft. 6in. and preferably not lower the oblique attacks from individual criticsprovide an item of attack. than zft. 6in. from the ground. The Ministry who each would like to be considered the Not so long ago the C.T.C. invited itsof Transport agrees that such limits are desir- one tailor of Tooley Street speaking for themembers to keep up a barrage of letters to theable and has consulted the Society of Motor rest of the cycling movement. Press, attacking any adverse comment. TheyManufacturers and Traders on the question It is well known that they speak for them-overlook the fact that this campaign, fomentedof making regulations accordingly.It seems selves, but because of their long associationthrough its own house journal, was known toprobable,however,thatsuchregulations with the cycling movement, have assumedthe Press, for many of them are members ofcan apply fully to new vehicles only and even proprietorial rights init. The triumviratethe C.T.C. here there may be practical difficulties in the of Tooley Street, namely the R.T.T.C., the The Press do not like inspired letters, andway of altering designs already in production. C.T.C. and lastbut least, the N.U.C., doit is not surprising that most of them went into Low -mounted lamps are a serious source of not represent the cycling movement.The"the waste -paperbasket.The spontaneoustroublebecausetheycannotbealigned R.T.T.C. speaks with the best authority forand uninspired letter cannot be mistaken andto throw the beam far enough ahead and at the those interested in racing on the roads, andif space is available it sees the light of print.same time avoid dazzling oncoming driveR. they are the most concerned with any actionLetters from cycling organisations are similarlyThe report recommends total prohibition of that may be taken by the authorities in con-easily recognised.They are mostly couchedthe use of lamps with centres less than aft. nection with road sport. in bitter terms, contain many familiar phrasesfrom the ground except in fog or snow. The R.R.A. can be ignored, since it is aand outworn arguments, all of which can be The Ministry of Transport is giving further small body and road records are very much infound in the columns of the house journalconsideration to this problem, having regard abeyance. referred to, and have been spouted from smallto the fact that where a low -mounted lamp We are not concerned with the views ofpublic platforms at unimportant club dinnersis the only device available to comply with the those who, as paid advocates, have remainedby the proprietors of the cycling movement,existing anti -dazzle regulations, such a pro- in the cycling movement to earn their livings.or by one of the tailors of Tooley Street. hibition might make the lighting system on We have no doubt that they have performed The League has the golden opportunity ofsome vehiclesillegal. Itispointed out, the jobs for which they are paid well and toputting cycling back on themap, and ofhowever, that the majority of such lamps are the best of their ability.They would beconfoundingitscritics.Letitnotplayprovided as foglamps, and drivers are urged signallylackingindutyif they did notinto the hands of thelatter by internalto use them only as such, and ensure that oppose any form of racing which tends todissension and internecine conflict.Thesethe beam is depressed and points to the left. put out of existence the organisations theycan only destroy what it is hoped to build up. represent. Inspection of Cycles This is a vital time in the history of theHeadlight Dazzle THE police have renewed their campaign British League of Racing Cyclists, and it is of inspecting schoolchildren's bicycles, time that its parts realised that they cannot THE Ministry of Transport makes a strongand of putting them through tests in the be the whole.The membership is rapidly appealtodriverstoco-operateinHighway Code and in riding.We have no increasing and their international linksasanti -dazzle measures along lines disclosed indoubt that this is done in the interests of with France, for instance, are now a reality. the Interim Report (attached) of the Roadroad safety, foritcannot be denied that The B.L.R.C. has been founded and guidedResearch Board as to the extent to which faultymany of these juvenile cycles are in a bad by men who by age or other circumstancesadjustment of motor headlights is responsiblestate of repair, and that parents are not always have no wish or hope of reaping financialfor dazzle. too careful in seeing that the brakes are reward for their labours, unlike the critics Recommendations in the report includeproperly adjusted, the tyres correctly inflated, from other camps. At this period the bid forsuggestions that headlamps should be setand that the bearings are lubricated and in control by self interested place seekers is anso that driving beams do not rise abovea correct state of adjustment. expected development. Such moves havethe horizontal and that passlamps should be At the same time,it must be borne in taken place in all other associations and thedadjusted so that the maximum intensity ofmind that the police have mot a statutory B.L.R.C. would be wise to purge the Augeanthe beam is dipped at least 3 deg. belowright to insist upon these examinations, nor stable now, and not to leave it like other bodiesthe horizontal, i.e., a aft. dip atraft. fromhave they the right to insist upon riding tests have done until the cancer on the corporatethe lamp.Neither headlamps nor passlampsand " failing " those who do not pass them. body has become too deep-rooted. should, it is urged, point to the right. The League has the great advantage that it The Ministry asks drivers to see that theirThe Neutral R.S.P.A. is not interested in anything but the sport.lamps are adjusted accordingly, paying atten- WE do not like the attitude of the Royal At the present time riders have fought fortion also to the following points : Society for Prevention of Accidents and temporarily gained the right to be the Adjust low -mounted passlamps and fog -in deciding to remain neutral on the question judges of their own appeal.If this is carriedlamps so that they point to the left, and dipof the increased speed limit for heavy vehicles. to logical conclusions they will next be selectingfoglamps in the same way as passlamps. The drivers have already protested against themselves for international cycling contests. If lamps have front glasses with flutingsthe increase of 20 miles an hour to 3o miles That position is quite fantastic.We appealintended to be vertical, make sure that thean hour, and they say that the increase is to the members to think of the League and toflutings do not appear as tilted from thebound to lead to an increase in the number cut out personalities. bottom left to top right when viewed from theof accidents in which vehicles are involved. It has done a great job of work in revivifyingfront. Time alone will prove whether they are interest in cycling sport, and it has done more Follow the maker's instructions. right in this respect.But surely the Royal' than any other cycling bodies within the Drivers are often tempted to tilt headlampsSocietyforthePreventionof Accidents whole history of the cycling movement toslightly upwards so as to give a better light,should have a viewpoint on the matter.It make cycling sport news. or fail to correct a tilt which has come abouthas decided to sit on the fence, being appar- Other bodies want hole and corner methodsaccidentally.Faultyadjustmentsofthisently afraid of upsetting the owners of such of running time trials as if they are doingkind, whether deliberate or not, cause dis-vehicles. 42 THE CYCLIST March, 1948 since the early days.In 1903, fora wager, he cycled Inviting Deathon from Loughborough to Leicester and back, riding one of the heavy machines of the period, with cushion tyres, the Road' over poor roads. He broke the existing record for the WHEN Grimsby High-journey by completing the trip in two hours and when ways Committeehe got back to Loughborough he finished up by riding agreed that four " Slow-round the yard of the Lonsdale Mitel in between Major Road Ahead " signs several dozen beer bottles set up to form an obstacle should be erected at dan- race course.Mr. Fuller was to have been paced on gerous crossings in the town, his trip by a car, but this ran into a ditch soon after the several members suggested start and several dozen other cyclists who were to have that" Halt " signs mightkept him company also dropped out, and Mr. Fuller be found more use as the met most of them on the outward journey as he was on others were apt to be dis- his way back. ' .. regarded. The Borough .... Engineer,however, ex- . . plainedthatthe Ministry Trammg Them Young of Transport did not usuallyT.TUNTINGDONSHIRE Education Committee have permittheerectionof .2.2. approved in principle a scheme for the testing of Halt "signs until thereyoung cyclists to see if they have sufficient road sense had been enough accidents to enable them to be on the road in safety.The I at the spot to prove that such committee have also approved plans for the formation signs were needed." And in local schools of units of the Cycling Safety League. so we have to wait until Castle Acre there have been a number Priory of accidents before we can The Indispensable Cycle Pump kinfolk.. do anything about it," com- AN ordinary, bicycle pump is part of the equipment stationof Pert of the remains ----...... mented one councillor. atthe North Lincolnshire railway of the great Norman. Normanby Park, a station which deals with a good deal of ironstone and steel traffic for the nearby steelworks. fortress and House Nightwork ! It is one man's full-time job to attend to the r5 or so of the Clunicic Monks AHORNCASTLE cyclist, pressure paraffin lamps on the station, and to be con- Vardar_ seen the other night totinually going round from one lamp to another when be footslogging along the they are alight, pumping them up with his cycle pump. road and pushing hiscycle, which was loaded withOnly a" short distance away there is a private railway Cycle Firm's Founder Dies a spade, fork, rake and other gardening tools and a track owned by a -steel company with electric cables THE death has occurred at the age of 51 of Mr large hurricane lamp, was asked what new sport he was running along it. Brook Hardcastle, of Tickhill Road, Doncaster, going to indulge in on such a dark night. He explained founder of the cycle and radio business of Brook that he was just going along to meet a friend and carrySweet Reward Hardcastle,Ltd. He started work in a Yorkshireout some work on his favourite bowling green by theTHE prize for attendance, presented at theannual colliery, but after a few years he started his own tinylight of the lantern as, he was busy during the daytime. dinner and prize -giving of St. Ives Wheelers, held cycle repair shop at Goldthorpe.Business prospered atthe Golden Lion Hotel, St. Ives, Hunts, was a box and gradually he opened additional shops, and withinNot for Speedsters ! ofchocolates . sent from Canada by a former club 20 years after he had opened his first shop there were member, Mr. A. Causton. There was a good gathering 45 branches.The business was turned into a limited A N Italian cyclist, whose idea of cycling is to ride company in 1928.Mr. Hardcastle, as a hobby, took" without getting the wind and rain on his face, hasof members and friends. The Mayor of St. Ives, who over and modernised the old-fashionedvillageofinvented a weather protection for cyclists in the shape proposed the toast of The Club, referred to the fact Thixendale, which he bought in1945, but the warof a combination umbrella and windscreen.It is madethat one of the local residents was one of the oldest years andtheirshortages of stiffenedmaterial and reaches almost from theracing cyclists in the country, Mr. George Dennis Day. considerably affectedhis ground on either side of the front wheel to well aboveMr. Day was a racing cyclist at Cambridge University business,and to -day the company hasthree mainthe rider's bead, being fastened to the handlebars andin the old penny-farthing days, and he received his branches. supported by a strut from the crossbar. Six transparent Blue for the sport. The Mayor also suggested that the plastic peepholes are provided so that the rider can see abolition of the basic petrol ration was a blessing in where he is going, that is, if he ever moves at all withdisguise for Cyclists. Still Going Strong ! this cumbersome contraption to absorb his energy. MR. CYRIL MUNDY, a cycle dealer and member Freak Accident of Peterborough Cycling Club, gave his fellow clubmen a surprise by turning up for a run on a Dursley-Old Landmark Back Again AMONG several unusual accidents mentioned in Pedersen cycle which he had acquired in the courseTHE sign of the Bell at Stilton, a familiarsight to the roadsafetybulletinissued by theChief of his business.It is in perfect condition and was not thousands ofcyclistsalong the Great NorthConstable of Lincolnshire is one in which a lorry isonce again bac'k driver by his presence of mind, was able to save a outmatched on the run by any of the modern machines.Road through Huntingdonshire, cyclist from serious injury or death.The cyclist was The younger generationinthe club weregreatly in its old position after an absence of some three years. amused at the appearance of the cycle but Mr. Mundy'The ironwork bracket holding the sign of the Bell was approachingthelorry when he suddenly became can stand all the laughs anyone cares to hand out andfound to have become very fragile through age, and agiddy and swerved.The lorry driver saw what was he hopes to ride it for many years to come.Anothernew bracket, an exact replica of the old one, has beenhappening so he shot out his arm and held the cyclist of the Club's unusual mounts isa tandem tricycle,produced by one of the few remaining craftsmen inup until he could bring the lorry to a stop.The Chief built by a member out of the frame of an old tandem,ironwork left in the country, Mr. John Bunning, of Constable's bulletin also emphasises the factthat a which also performs perfectly.This tandem took partStamford, Lines, and now supports the newly paintedcyclist who wishes to reach home all in one piece should in the same run, as also did several tricycles. sign.The Bell is considered to be one of the oldestresist the temptationtocarry large parcels on his inns in England, being over 45o years old, and its old handlebars. walls can remember the days when beer was thicker Which Way? than water. Takeit Easy, Legs ! AMERICAN cyclists, who prefertheir cycles to NEW type of rear light brought out by an American looklike motorcycles, would also sooner rig up Afirm consists of twin lenses, each with an arrow Club's New Trophy some mechanical attachment rather than pedal, and pointing either to the left or to the right.From aATROPHY is being presented to Doncaster Wheelers their prayers have been answered by the marketing of control switch on the handlebars the rider of the cycle by the family of the late Mr. J. A. Bates, a keen a lightweightbicycle power -plant.This comprises can light up either arrow at will and indicate to following rider with the club for 21 years, and will be presented a small engine, complete with petrol tank and all the traffic which way he is about to turn. each year to the winner of a specified time trial, it was other gadgets, mounted above a single balloon-tyred stated at the club's December general meeting.Refer- wheel which is half the size of the normal cycle wheel. ence was also made at the meeting to next year's plansWhen the cyclist feels he wants to rest his legs, he Helping Themselves for the club which include the promotion of an open simply removes- his rear wheel and chain and attaches nOYS at Rossington Modem School, Yorkshire, are 25 -mile T.T. race for men in April and a similar eventthe power unit and connects up handlebar controls. .2-2 being taught to stand on their own feet and notfor women riders later in the year.The club's " 25,"They away he goes in a cloud of blue smoke, with to expect to be spoon-fed by the State.Police checks held each Whitsun for several successive years forlots of smell and noise, to enjoy the beauties of the of cycles are all very well, but they take up the time of" middle -markers," is being discontinued. countryside. policemen who could Very well find more important work to do, so the boys at Rossington, under theRintaku ! Change of Speed

-supervision of their science master, Mr. J. Webster,THAT is what the Japanese shout for these days whenMEMBERS of the Loughborough andDistrict now carry out all normal repairs to their bicycles.Since they want a taxi-and up comes a pedal tricycle. Motorcycle Club have turned to cycling now the scheme started not a, single scholar has been involved Owing to the shortage of petrol and motor vehicles, thattheir basic petrolrationhas vanished.Their in a road accident due to a faulty machine. these tricycles have been developed to fill the gap.a first cross-country trial on cycles proved most popular, The passenger sits in a small enclosed cab over thein spite of the mud baths, water -splashes and other two rear wheels while the " driver " pedals away ininconveniences so beloved to motor cyclists.Several Rousing the Worst Instincts front. Only one passenger can be carried in eachmembers said they had never enjoyed themselves so WHEN it was suggested at a meeting of Grimsbyrintaku, so if a Japanese takes his girl friend out formuch before and even the rider who skidded and fell Road Safety Committee that the town shouldan evening's entertainment he has to hire two " taxis." headfirst into a water -filled ditch that did no: smell have a squad of " courtesy cops " to go on duty at rushDuralumin forms the greater part of the framework of of violets, was in favour of many more similar events. periods a member suggested :" I am beginning to think these vehicles in order to lighten the driver's load, but One woman rider made a crash landing in a thorn bush loudspeakers are a curse, and that they do no good in even so he earns his money. but she, too, remained undaunted, so perhaps by the persuasion.In fact, I am beginning to think they fail time the basic ration is restored we shall have made in their purpose.They rouse the worst instincts inAnother Mill Vanishes quite a few new converts to cycling. people."The Chief Inspector of Police pointed out that there was no actual law to prevent cyclists doing A PICTURESQUE spot on thotinain road from Derby such things as riding three abreast if they wished, and"to Loughborough, the ancient Dishley waterrnill, Yorkshire Section of B.L.R.C. he thought people would resent being told not to do isbeingdemolishedbytheLeicestershireWar something that was not forbidden by law. Agricultural Committee. The waterwheel and the mill A T the annual general meeting of the Yorkshire are being removed and the millrace and pond drained 2.2Section of the British League of Racing Cyclists, in order to prevent flood water from the Willowbrookheld on Sunday, January ttth, at the Black Bull Hotel, Sir Walter Helps Exports backing up in very wet weather and overflowing the --Otley,there wasarecord attendance of delegates surrounding land.Records show that the mill was indespite the atrocious weather conditions.One service ASTATUE ofSirWalterRaleigh,measuring existence in the 17th century, when it belonged to the delegate had ridden from Louth in Lincolnshire and 8ft. 6in. high and standing on a 4ft. 6in plinth, Abbey of Gaiendon.With the demolition of this mill had to ride back the same evening. was a prominent feature of a private exhibition ofthere will be only one working mill left in the Lough- G.Whittaker,ofBradfordR.C.C.,waselected advertising models held in London for foreign buyers. borough district, that in the village of Cotes. chairman ;W. Woods, of Vegetarian R.C., general Sir Walter's mission in life will be to assist in the ever secretary and press secretary ;D. Padgett, of Bradford expanding export drive of the Raleigh Cycle Company, R.C.C., event organiser ;and K. Farrar, of the Bradford whose Nottingham works are playing a very considerableCycling Memories Co-op Velo club, was elected treasurer. part in restoring Britain's economy. The figure, whichMR. EDWARD A. .FULLER,of Wymtswold, The secretary reportedthatthere were now r6 is most realistic, is one of the products of the Lough- Leics, who hasjustcelebratedhis diamondclubs in the section, three more having joined during borough firm of Models (Leicester), Ltd. wedding anniversary, at the age of 82, has been a cyclist 1947. March, 1948 THE CYCLIST 43 AroundtheWheelworld By ICARUS The R.T.T.C., that uneasy bed partner ofat law, fall solely on the secretary or councillors More Lighton Massed Racing the N.C.U., supports their policy.G. H. S.,responsible for such proceedings, and there LAST month I dealt with the criticisms byhaving taken up an attitude which cannot beis no right of indemnity against anybody." G. H. S., in a contemporary, of massedsupported by the facts, should withdraw from start racing and methods of running itasthe fray, in which all victories have gone toCycle Makers' President disclosed in a talk by the general secretary ofthe B.L.R.C. FOR the fourth year, Mr. George Wilson,. the B.L.R.C. before a cycling club. When G. H. S. was the secretary of the Those criticisms reminded me of the lines : C.B.E., managing director of Raleigh C.T.C.Iconductedcorrespondence withIndustries,Ltd.,Nottingham,hasbeen " I do not love thee, Doctor Fell, them on this matter.I asked them whetherelected President of the British Cycle and The reason why I cannot tell ; a postal vote of its membership had been takenMotpr Cycle Manufacturers' and Traders But this alone I know full well, on the subject in view of statements in theUnion, Ltd.Mr. C. Douglas Terry, of I do not love thee, Doctor Fell." Press, to which the name of the C.T.C. hadHerbert Terry and Sons, Ltd., Redditch, In other words, G. H. S. does not likebeen coupled.The answer was that C.T.C.and Mr. J. Y. Sangster, of the Triumph massed start racing. policy is determined by its Council, and noEngineering Company, l., Coventry, have Now, G. H.'S., ex -secretary of the C.T.C.,postal vote has been taken or is needed onbeen elected vice-presidents for the third in 1943issued a statement to the Press onmassed -start racing. time. massedstartracing,andthisstatement This is another democratic [sic] body like included a reference to those running massedthe N.C.U. ! They did admit that theyR.R.A. Triennial Dinner Cancelled start racing asanumber of hot-headedconducted more massed cycling than any other THE Minister of Food hasrefuseda youths. Theseremarks weretakenascycling club, but apparently they had not licence to the R.R.A. for more than representing the views of the C.T.C., ofsufficient unity of purpose with the othertoo guests at their proposed Triennial Dinner, which he was then Secretary.Finally, afterbodies to have written to the Home Office andor rather, the revival of the Triennial Dinner, representations, he had to admit that the viewsthe M. of T. on the matter. They were willingsince for understandable reasons the function were his own, and I believe he withdrew histo wound yet afraid to strike. was not held during the war.The possibility statement about " hot-headed youths." Although our contemporary has devotedof running a buffet, instead of a dinner, was Nothing daunted, after his attack to whichtwo pages to the subject, thereisnot anot foundtobepracticable.The idea, I referred last month, he devotes anotherscintilla of sound argument against massedtherefore,iscancelled.Thisisapity, full pagein a contemporary toa furtherstart. because the members of the R.R.A. are not attackentitled" More Light on Massed afforded an opportunity on many occasions Racing," and the vehicle for his attack are two" IstheN.C.U. anIllegal Body ?" for getting together, and it is now over nine letters of disagreement with his views which, view of the sorry position in which theyears since the last function.There is very he admits, are " reasonably restrained exceptINN.C.U. now finds itself, I was somewhatlittleinterest at the present time in road for a slight sting in the tail of one of them." amused to read the following in a cyclingrecords. G. H. S. expressed the hope that his articlejournal published in 1898 : will " remove and sterilise " that sting. In my " It is not a little extraordinary that forTribute toNevill Whall view it does not. His article is merely anotheryears the National Cyclists' Union has been THE NationalCommitteeonCycling attack.His remarks call to mind the wordscarrying on a very praiseworthy but wholly of George Herbert (1593-1633) : have sent the following resolution to illegal existence.Every good cyclist wishesMr. Nevill Whall, who has resigned asa .. . striking, sometimes a friend, some-well to the Union in its proper work, whichC.T.C. representative on leaving the C.T.C. : times the engineer." is that of regulating race meetings and kindred" The National Committee on Cycling have Now, it is unfortunate for G. H. S. that hematters.When, however, it steps outside thereceived with real regret the news that they referstothe" Three Tailorsof Tooleylimits wisely prescribed by its founders, andare no longer to have the benefit of Mr. Street," which was the title of a leading articleattempts to copy the methods of its greaterNevill Whall's ripe experience.They wish in this journal dated January, 1944, in whichsister club, and, whether from envy or malice,toputon record their appreciation of all that the N.C.U., the R.T.T.C., and the C.T.C.tries to supplant in the public mind the credithe has done to maintain the rights of British were likened to those three tailors who, indue to the Cyclists' Touring Club by inter-cyclists and their own sense of the loss to addressingapetitiontotheHouseoffering with matters of touring and similarthem of his quick mind, tact and judgment." Commons, "began :" We, thepeopleofquestions,itissurely time to raise some protest. Take one example :the action of the Special tributes to Mr. Whall were paid England demand. .. ." The distinction here by Mr. A. P. Chamberlin, as secretary of thp is that on the matter of massed start racingUnion against a railway company on theN.C.U., and by Mr. H. R. Watling, National G. H. S. gives the impression that he is thequestion of passengers' luggage seems to beCommittee chairman, who saidthat they one tailor of Too'ey St. absolutely without justification.The Unionhad always found him active in debate and One of his correspondents in dealing withhas no right to spend one penny of thecourteousandableincontroversy.He Government oppositionto M.S.,says :members' money without personal consent ofadded that they had the very special pleasure " This is an unfortunate, but it would seemeach member, and the writer knows of manyof welcoming Mr. R. C. Shaw as Mr. Whall's an inevitable consequence of the violent anti -members of the National Cyclists' Union whosuccessor. massed -startandanti -Leaguepropagandaare convinced of the futility of contending that campaigndirectedbytheN.C.U.,thecycles are passengers' luggage, and wouldThe Demon Cycling Club R.T.T.C., and a cycling journal. The popularnever sanction the expenditure of money in opinion is that the damage done to the cause,such an undertaking. AT the annual general meeting of the of cycling by the B.L.R.C. is negligible, but The Union undoubtedly makes a profit in Demon C.C. it was reported that the the damage done by your persistently biasedmany ways ;the application of that profit isclub membership had increased by too per The fact that it makes a profitcent. The motion to inaugurate a club articlesisregrettably enormous, and whoimmaterial. season was passed knows where it will end ! "G. H. S. in hisis sufficient to bring it under the Companychampionship forthis reply to this says that the apologists for theActs, and to renderitsregistrationas aunanimously.The principal officials elected League have said that if and when the crashcompany necessary. Any association of awere :president,J.Beddow ;chairman, large number of persons carrying on businessJ. W. Page ;secretary, A. G. A. Wilkes ; comes the fault will lie with those who said press secretary, R. A. V. Page. the B.L.R.C. was making a mistake. at a profit is absolutely illegal unless properly What they have said is :" If and whenregistered.The result is that the National the crash comes," time -trials will go down withCyclists' Union is only a gigantic partnership,AnnualDinner of B.L.R.C. (London Section) massed start, and those responsible for theand that each member is absolutely entitled THE third annual dinner and dance of crash will be those, including G. H. S., theto be personally consulted before anything is the London Section of the B.L.R.C. N.C.U., and the R.T.T.C., who, betweendone.The liabilityofeach memberis was as successful as the two previous.It them, have fomented opposition to M. S. on -wholly unlimited and, unlike membershipwas held at the Victoria Hall, W.C.2, with the flimsy pretext which we now know to haveof the Cyclists' Touring Club, may involvethe new president, F. S. Durman, in the chair. been based on false premises. the surrender of all one's property. AnyThe speeches were all limited to not more Mr. A. P. Chamberlain, at a meeting ofthecontracts or agreements made by the Nationalthan four minutes.I hope that the dissension club where Kain was the guestspeaker,Cyclists' Union are really worthless to theexisting will disappear.Disagreement may publicly admitted that he had conductedUnion, and are only valid as far as concernsbe healthy, but dissension devastating, as correspondence with the Home Office andindividuals who sign such agreements.Or,Mr. F. J. Carom, in responding to the toast the Ministry of Transport opposing massed -to put it plainly, the loss arising from anof the Press, said, the part can never be start racing. hotel agreement, or the costs of an actiongreater than the whole. IP 44 THE CYCLIST March, 1948 will be equally difficult.The news is not encouraging, and we had hoped for better things two and a half years after the end of the war.So I have been looking Wayside Thoughts into the condition of my little stock of bicycles, and one or two of them have gone into dock for expert attention, so that they will be fit, and ready to meet ByF.J. URRY my needs, and possibly those of my friends, when touring time comes roundagain.One ofthesemachines pocketand theirinclina- neededa new pairof rims,fortherear one,'of tions, and far too often thehiduminium, had worn completely through onits lure of cheapness wins.It brake track, and the front one was not much better. is the easiest thing in theOn the other hand, a thirteen -year -old bicycle, also world tobecritical,but fitted with alloy rims, was in perfect trim and only one of the most difficult to needed re-spoking to make the wheels firm and reliable. take the advice of exper-'This alloy. was of Italian origin, and the rims have ience.We listen to it, yes, stood up to some 25,000 miles of regular wear without buttoo- oftenwiththe wilting under the braking strain ;soit would seem thought we can do better. that our British product needs the addition of a hardening Perhaps I was fortunate inelement in its make-up.I must, too, have several discovering the truth of thissaddle tops re -blocked to restore them to a reasonable business of choicein the shape, forI do not like using the adjusting bolt for very early days of cycling. tensioning purposes:it pulls the saddle out of shape and reducesitscomfort.Chains are going to be Eavesdropping difficult to obtain, I hear, and some of the wise lads, incomprehensive discovering supplies in small country depots during THEnerve of some peopletheir week -end peregrinations, are buying them up to say cycling is hard work against the certain need of service.I have, fortunately, when they know so veryone new bicycle, and I'm saving thatfor the long little about real riding goesjourneys and the touring, using those models with onand,ifanything,in- doubtful tyres for daily riding, and the intermediate creases.I overheard a pre- samples for the leisurely week -ends when the repair arranged conversationthe of a puncture merely adds the opportunity of a smoke other day which was illumin- to the journey, My waterproofs are growing old and ating.A certain friend ofnot too reliable, but I find that by turning the cape mine did the job, simpleback to front it will still do its job reasonably well on enough, by putting me in athe seven miles out and home journey, while the better room next to that of the dir- one and a decent pair of leggings hang in a dark corner . awaiting the time when they may be called upon to ectorof the concern, andthen defy the spring and summer storms along the ways opening a conversation on I hope to go. Suc "...-tkcPloor this subject of cycling. And it ran something like this: One of Britain& rettiee villa9er " Well,'James, I don't care what you say, you will neverPlanning in Advance convince me thatfellow Urry enjoys riding to work in the rain." That is sufficientWHICH reminds me of 'a little meeting where' four The Marvel to give you a basis to the arguments that followed.The of us tentatively discussed the possibility of a BEFORE the news reached the pressof this countryfact is that the speaker had never tried this manner 1948 holiday inthe Highlands.The subject arose I had a letter from an Australian friend tellingof transport fora single day, ,never mind, about a wetout of a report that the remote spots of fair Britain me of the remarkable endurance feats of a 73 -year -oldone, and his opinion as evidence against cycling waswould not be overcrowded during the petrol -less days cyclist, one Ernest Old, a native of Blackpool, and anworthless.He willapplyforpetrolforbusiness of early summer, and the four members of this holiday old soldier of the Boer War.I did not believe them,purposes and get it, being head of a big firm whose syndicate, the youngest of whom was sixty-four, could and I wrote and said so, for the stories savoured toomain business is to equip cyclists.It is a trifle Gilbertian risk the straight tour from place to place and renew much of those tyre testimonials: " It has been riddento think along these lines,to imagine people who owe the adventures of their Youth, a little more steadily 26,000 miles without a 'puncture and is still good foreverything to cycling sitting smugly in an office andperhaps, without discomforting their years.A Scots Many more centuries."I have never seen the tyremore or less denouncing the folk who ride because they friend of mine tells me that June is usually 'the best with so long and virtuous a mileage, and didn'tlike riding and are free from the costs and burden ofmonth for weather north of the Great Glen, and as that believe a man beyond the " allotted span " could success-motoring.In a perfect world one would imagine suchdate falls before the Scottish holidays begin, it should fully undertake a journey of a thousand miles in a triflefolk would be the first to applaud the bicycle and allbe an ideal one for our purpose.So the project is under to days.But the reports inform me that thisit has meant and still means to emancipation and health ; taking shape.We have " begged off " for a fortnight veteran has won the cycling marathon from Melbournebut then, the perfect world seems as far off as ever, from the domestic hearth, we have settled on a train to Darwin and back, $,200 miles, in a couple of months.and those among us who have discovered their littlejourney to Inverness, we have agreed to " drum -up You will agree that it needs an extraordinary man toperfection of living and moving find it most difficult toin true Scots fashion for lunch and tea, to cut the,miles make such a journey, and when you reflect that therouse a tiny desire in other people, and especially itaccording to the weather, the wind and the mood of individual in thise case was 73, you cannot fail to beseems to me, people who, possessing money, imaginethe moment, and to telephone from bed to bed, as it astonished.I am ;for I know what cycling endurancethat which it purchases at high prices must be better were,tosecure our comfort.Yet, evenso, when is, and at leastI know something of the limitationsfor them and their well-being.Ah !but they havethe itinerary was examined it was found to provide imposed on activity by the passage of time.I do notforgotten the simplicities ;the individual freedom thatjust over goo miles of riding and some of it was pretty recommend you to emulate such afeat,but quitemarries so happily with exercise and bodily well-being, tough for ancient pedallers.What a pleasure itis to seriously I do suggest there is a value in cycling whichand lives joyfully ever after.I am not so poor thatpore over the maps and anticipaffi a summer to come as a health preserver and an agent for activity is still aI do not count these things beyond price and look toand all the quiet joys of care -free wandering over the long way from realisation by the elderly.Recently Ithem to fulfil for me the comely comfort of happiness. lonely road 'twixt Inverness and the Ultima Thule of walked some seven miles over plough and etubble Groats and Cape Wrath.It may be a tiny adventure and through roots in search of game, with an old friend in embryo compared with the great expeditions, but who found the Vigour too much for his comfort andStill Waiting it is all your own, and the thought of it gilds the waiting rested on many beats while I tramped on. We are of a time of winter and preserves in you the desire to keep similar age, and when later in the day we were enjoyingTHE buying of good bicyclesisnot going to bereasonably fit and active for that moment. when joyous the refreshment of tea he told me the kindof,fool he easy, I am told, and equipment and replacementsactivity will earn the dividend of great happiness. has been ever to give up his cycling." That is the reason you can stick it and enjoy the long day when I wilt half -way through and shall be stiff and sore for a week."And probably he is right. Keep to Quality TT is the way of the world after having bought some- thing1- cheap to brag about it,not that there' are many cheap things to buy at present, or, to put it a more truthful way, the " cheap " things are dear.I hope I am not given to bragging, for itis an unfortunate characteristic in anyone, but ifI were to fail in this matter I think I would rather brag of my purchases in the sense of how good they were rather than how cheap, and this specially applies to bicycles and every- thing connected with them, from the actual article to the raiment you wear.The word cheap generally carries a seeond-grade meaning, and never more so than when it is used in connection with bicycles.Of course, many people do not believe this, for bicycles loOk very 'Much alike and one cannot peer under the enamel or the plating, or test the bearings for perfect finish, hardness or alignment, which is a pity, for if the difference between the goods was manifest to the unini- tiated, I am sure the quality machine would more easily become the common choice of riders.My energy is the driving asset of my cycling ;how itis used or conserved, expended pleasurably or painfully, is largely due to the type of bicycle Iride,its gearing And its equipment.So when I buy I have this fundamental fact in mind ;I am the motive power, and my enjoy- Before the pupils of the Putney County School ment of that exercise is mainly dependent on my choice. In this matter I am not greatly concerned with looks ; for Girls could ride their cyclesto school, it that is a secondary consideration, but with reasonable was necessary for them to pass certain road tests. lightness, good tyres, moderate gearing, easy, effortless Cycle steeringandcomfortableseating-yes,theseare testswereheldintheplayground. important, and if such advice could be quickly and In the illustration some of the girls are seen asily demonstrated the quality of cycling would at -doing their road tests under the vigilant eye of once increase.Butitcannot, and would-be riders s lust depend on the advice of experience, their own a local policeman who came along to help. March, 1948 THE CYCLIST 45 Now is the time to order "No other tyre your new C.B: will really satisfy DISCUSS YOUR NEEDS en" AND SPECIFICATION your WITH"C.B."SALES invitesofmachin,to AND SERVICE DEPOT Butlertype club, MANAGERS AT : Claudfor any dime touing,and me now" WANDSWORTH Straptrack, 101, East Hill, S.W.I8. oad, anglesrecornmendedsettled Manager :George Brooks C..B.details the youror tothese for Tel.-BATtersea 1381 sions Get inhand C.B. no,N LEWISHAM design. 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anaz March, 1948 THE CYCLIST 47

By CYCLORAMA H. W. ELEY BicyclesforChristmas ON Christmas morning, and since, what alot of gleaming new bikes around the roads . . . many of them juvenile types, gifts from " Santa."And what joy they must have brought to the hearts of kiddies, and " big kiddies "! I cannot think of a better gift than a bike; and we should he gladthattheBritish cyclemanufacturei-, by dint of hard work, good planning, and an appreciation of the home as well as the exportmarket,managedto _providethe retailers with such good quantities of cycles. I believe that the industry has a great record in these difficult post-war days, and we do well to applaud the work of its Laders, and of the men and women at the benches. Looking Forward yES!-forward to Easter, for itis not so very far away!And, on these March nights when the wind is chill, and I feel like .kiskqe,.;:-. -,,e,;\<:-`.'otr;,'-'' CleV. an hour or two by the fireside, it is good to 4`ZUe \t; take down some old maps and note -books ,, ( Av. and conjure up memories of past tours and toham,a\ The picturesque windnt.ill. travels.Pipe well alight . . . the fire burn- Row a priyate dwelling house ing brightly . . . the old spaniel dreaming oeiba-ro but retinirtsj all di original eak good doggy dreams on the hearth -rug . A\\,\* \''ckamee how good to ride, in Memory, down the old roads again and recapture some of the hap- piness of former years.That ride to Devon, some of the associates of her late husband!with memories of old Wiltshire and Somer- r SalutetoSpring set towns and villages ;that good tour in WHATEVER the weather may be in the" Faed "willnever beforgotteninthe business . . . and long .may his widowthe Lake district, when we entered into the mad month of March, my calendarsurvive as a link with grand old days! magic land of mountains and tarns, of noble tells me that, officially, spring com- sheetsofwater,tree -fringed and -unsur- mences on March 2ISt . . .so I salute theDoes Cycling Get aFair Deal? passed in loveliness ;that year when the call new season and vowthatIwillatanTHAVEwritten on this question before, usto the homely little early date sojourn out into the countryside of the road took .1; and recently, at a club dinner,I wastowns and hamlets of East Anglia ... to the ; and searchforthevirginal snowdrop intalking to my neighbour at the table andlandofConstable and Gainsborough,to ; some grassy dell, and find joy again in theit cropped up again.Do the newspapersquiet lanes, down which good Suffolk punch golden gorse which spangles the common-tend to ignore cycling as a national move-horses ambled with great waggons which that hardy bloom which is with us almostment ? My good dinnerneighbour wasreminded us of " The Hay Wain." And then all the year round, however bleak may beemphatic that they do, and mentioned howthere was the memorable year when we the wind on the heathand however themuch space, even inthesedifficultdays,cycled, a goodly little party of us, into Cen- snow may fall.And soon it will be catkinthey manage to give to other pastimes andtral Wales, to the beauties of Radnor and time, and we may rejoiceagaininthehobbies and interests ;well,itisa pointMontgomery-and we recall how we loved 1 ' purplish buds of the alders down by theof view, butI must notenterinto anythe hillsides, dotted with Welsh sheep, and stream and in the yellowish catkins of thecontroversy on the matter ;I could wish,the rowan trees, with the berries like rubies, willow which hangs so gracefully over theverystrongly,that more space could beglistening in the morning sun.Yes !not at water's edge.Yes, salute to spring! devotedtocyclingandcyclists. . . andall a bad plan to have a " touring evening " I do not forget that we number :,ome ' soby thefireside . . and make plansfor The Benevolent Fund to 12 millions!Let us leave it at that. Easter ! the big propaganda drive FOLLOWINGtosecure new members, my good friend Heysom,the general fund organiser, tells me that good results have been achieved, and that there isa new and lively interest being displayed in the fund and its opera- tion. Atthe moment,asisfairlywell known, the membership is not open to non - -" manual workersinthecycle and motor trades, but this phase of the matter has, I know, received very careful thought, and possibly some day the scope of the fund will be extended.In any case, it is a fund ;. worthy of loyal and good support, and I am proud to have served on the committee which aimed at making its good work more widely known. And in Heysom, working

; ;with my old friend A. H. Dawson, the fund --.__-+131111.-11 ; , 1 has a great stalwart. . - , ,Proud Moment TTwas at the recent benevolent fund ball, J1 held at the Lyceum-and it was a proud t, moment for me, because I met Mrs. A. J. Camber Castle Wilson, the widow of the founder of the q_qJaPa4.- fund.My friendship with her goes back Oa the edge of the wild 430o4li ke?nineg Marshes this now over Many, many years, when her late hus- Tuned Castle onetguarillesl band was the chief of the famous Wilson from.sea attacks144the Agency, which handled so many motor and Plew4. memaf41. of alliedaccountsintheadvertisingworld. #te or,94,0 .rea leue caa be "Dhpizty teen a4 soave Mrs. A. J. W. looked well . . . and how delighted she was to renew contacts with . . 48 THE CYCLIST March, 1948 I called to see the man, and was given lunch.Then, with marked generosity, my friend (an oldcyclist) offered to give me a lift over the long hill facing his, My(a, Point of View house, which he told me would take me zo minutes' walking time.I accepted this offer. My bicycle was put on the luggage -rack of his car, and inless than five By " WAYFARER " minutes I was on the ridge.With the wind helping me I flew down the other side, and went steadily onwards, changing my plans from minute to minute. Ultimately I had tea in Bridgnorth, and then commenced i a three-hour ride in the dark, with the hope of being home by q p.m., as usual.It was a very black night, and the rain was sousing down with energt worthy Of Neu.e0u.": a better cause.But in less than half an hour a change

Isle of Viciltt! came over the scene.The wetness ceased, th'e clouds rolled off, and millions of stars came out, causing the blackness of the night to melt away.So, with 69 miles 'The old capital of rite on the tally (plus 66 miles for the previous day) I Island the Iowa. 611 arrived home on the dot of nine, well content with my Pictured Imre, is nog expedition to (and from) the Lonely Inn. loutk. Hostel . used as a Suicide Pact ! AFEW years ago there was a movement, which I considered rather unreasonable, to interfere with cyclists who carriedthings(thustosome extent hampering their movements) on their machines.The gardener was going to be forbidden to carry a scythe when riding a bicycle ;the roadman was going to be told that he must not carry a shovel as he rode to his work, and so on.I viewed these efforts at interfering' with the convenience of what we call the working - classes (and others) with some -concern and annoyance; it seeming to me that the powers -that -be were tackling an aspect of the road problem in the wrong way-as usual. The whole thing ultimately fell to .the ground, or perhaps it was that the coming of the war put it into cold storage, where it will remain until the interferers decide to trifle with the idea again. The matter was revived in my mind a few days ago, when I was inthe pleasant Warwickshire town of Nuneaton. There I saw-and it must be admitted that I was rather horrified at the sight-two men on bicycles carrying a ladder between them. There is not much iii that perhaps, but it was the method which appalled me, than those I had already traversed. It was an easy ride- for the head of each man wag thrust between the rungs, Desperate Remedy " jam " after the " medicine " of the aftemoon-and one at either end of the ladder, and thus they progressed THERE was a transport strike inthe great city which I felt well content on docking, with an exact half -centuryalong a main suburban road bearing a fair amount of I ornament with my presence, and enrich throughof miles (17 and 33) to my credit, mixed traffic.For a moment I wondered whether I the medium of taxation, and the circumstances con- was in the presence of a suicide pact, it appearing to me strained a ,bright lad to write to the local newspapersThe Lonely Inn that, if anything untoward happened, one of the men to express his thanks to the strikers, because, through (both, perhaps) might easily break his neck. The two the absence of buses, he " discovered a long -lost joy-CONSCIOUS of a great urge tospend a night at themen pedalled gently out of my life, and I can only hope a sharp walk in the crisp morning air." This unwonted Lonely Inn, which -Stands in an elevated position that they both survived a practice which did appear (if compulsory) spot of exercise caused him to findin the Welsh Marches (and which, last August Bank to me to be really risky.Possibly, however, they had greater pleasure in eating, and, when he went to bed,Holiday, provided me with an excellent lunchl, I wrote had years of practice at the job and knew exactly what he slept the sleep of the just.I am not sure whetherand obtained accommodation.Incidentally, the ex-to do if danger threatened. this is not all very pitiable.There is no law againstpedition would enable me, who am always frivolous in taking exercise, and how much better thousands ofthese matters, to celebrate the advent of November and people would be, men and women alike, if they made athe arrival of the occasion for putting hack the cloek. We Oddities - point of walking or cycling to and from their work or,Actually, too, I had a business call to make on my way the whole,I am prepared to believe that we if the distance is too great, walking or cycling part ofto the Lonely Inn, and it was difficult to discern any ONcyclists are, in a way, oddities. We-some of us, the way.I write as a practical exponent of the gospelother method of achieving this visitexceptat con-anyhow-go out in very hot weather, and pretend to I preach, and I know from years of experience how much siderable expense. enjoy the conditions. We go out in very cold weather, I owe to the bicycle and to my two legs, in the way of I am at present living in such a hectic whirl that there when the fireside possesses such allurements, and we health, convenience, money -saving and comfort-and,was no time to go into the question of distance, though come back and talk about the grand day it has been. inthe coldweather,of blood-circulation-and,as a glance at the map suggested that the ride was wellWe go out on wet days and windy days, and thus regards cycling, the time saved. within my compass.For one deplorable moment Iflaunt our " queer idea of pleasure." We are strange dallied with the prospect of accepting railway aid, butcreatures who actually cycle in the dark, when, as is side-tracked the idea.Railway aid without speed is, in well known, " you can't see anything." We spurn the Medicine... my view, useless, and no speed was available.Thecomfort and convenience of bus and tram for our worka- BECAUSE of a late start, I went by almost the directjourney ultimately proved how foolish it would have dayjourneys,preferringtosplashthroughthe route to my destination, intent on having a farm-been to cram my 'dollars " into the maw of a rapacious (sometimes) filthy conditions of the winter-preferring house tea.It was a bleak day, which stung bare knees, train, the direct distance being a trifle over 6o miles. to get wet and dirty-preferring to mix ourselves up with bit gloved fingers, and had a watery effect on eyes andI fought the wind to Bridgnorth and through Corvedale ; congested traffic. We do all these things-and survive,. nose. Nevertheless, I enjoyed the outing, and rode fast, I went off the normal route to make my call, and wasAnd not only do we survive, we are actually all the wherever possible, in order to maintain circulation.there given a nice tea, which was some consolation forbetter in health for our method of living.Yes, we ate The route chosen wad hilly one-the hilliest leadingmissing the man I wanted to see, and then, in theconfessed oddities. out of the city containing my dwelling-place-so thatdarkness of the night, with a promise of rain, I com- There are a few greater oddities among us.One of plenty of foot -stamping was available.The sun went pleted my journey, climbing steadily to the Lonely Inn.these, in my view, is the cyclist who believes in carrying off duty in a wonderful blaze of colour, and my farm- A grand wood fire, and a company of six younga mirror on his handlebar and thinks we should all do house was reached in the greyness of the gloaming. Thepeople groupedaboutit,providedasatisfactory the same. He asserts that the mirror is indispensable, front door, " made-up " (as they say in this part of the welcome, and it was not long before I was " doing myalthough he carefully refrains from saying what happens country) for the night, was quickly opened, and thestuff " with an excellent array of food-very hot soup,when-or if-he is riding in the rain, and the mirror is lack of fire in the dining -mom was atoned for by theroast goose and the usual etceterasfruittart andconcealed under his cape.Moreover, does the mirror introduction of two paraffin lamps, which providedcustard, and biscuits, butter, and cheesT, with coffeepossess any real value in the dark ?Then there is the both light and heat.Nevertheless, the temptation to to follow.The Lonely Inn I found to be a curious oldoddity who loads up his bicycle with all the latest gadgets, linger for very long after an excellent tea was absent. place, built below the road, which is on a level with including bits of leather round the hubs, a motor horn, the upper floor.Actually, at the end of a long passage,a speedometer, and a" Stop " sign.There is the from which the bedrooms open, is a door straight onoddity who thinks that the use of the bell by cyclists .. And lam to the road.There are odd corners and bends, and Ishould be forbidden-who thinks thattoring your rOR a moment or two,I found that the night wastook home with me evidence that one of these hadbell savours of dictatorship, meaning " Get out of the -L. extremely dark, but my eyes gradually became used " got in my way " 1The machine which normallyway ! "It may he suggested here that the wise cyclist to the conditions, and it was quite easy to see.Sittingmakes the electriclight was onstrike, and smallalways carries a bell, but uses it as little as possible. secure behind my gas lamp I made good progress, and, paraffin lamps abounded.The Lonely Inn containsThere are occasions when a bell is indispensable.It when the murk which was strewn across the sky moved two bathrooms, each with " h. and c."Before retiring means anything but dictatorship ; it means nothing more away and revealed a marvellous display of stars, the for the night I walked abroad in the pouring rain, and than :" I'm here.Sorry to disturb you, but may I sable night was toned down.I had earned the tail windwas struck by the intense silence and the loneliness-come along ? "And there is the oddity who seriously which was now my portion, and the bleakness that hadtwo things I sought.Then, in this deadly but con-suggests that the problem of road accidents at night-time characterisedtheafternoon was therebymitigated. soling quietude,. I climbed into bed, blew out thewould be solved if all our roads-the whole i7o,000-odds, Over deserted roads and lanes I forged steadily ahead, paraffin lamp, and went to sleep, being disturbed onlymiles of them-were flood -lit.That suggestion has meeting next to nothing, and thoroughly enjoying theby [that I took to be the scurrying of mice in the raftersactually been made in print.Obviously, it was made seclusion. I climbed up 'through the hooded valleyabove me. without the slightest thought, and it always seems to which so often falls to my portion, and topped the high Sunday was what people would call a "bad" day.me that a moment's consideration of the proposal from hills forming a rampart between the farmhouse and myIt rained and it blew, and, as the day grew older, thethe expense point of view-ignoring all other aspects of home. Then, instead of going straight ahead towardsconditions worsened. As I had to call again on the manthe matter-would he sufficient to condemn it. Were it the myriad of twinkling lights which, at night-time,I had missed, my homeward route was dictated for medesirable to flood -light all our roads-and I, personally, mark the great city of my dwelling -place, I made an-in part, at any rate.Otherwise, I would have " madeconsiderithighly undesirable and deplorable-the extension to my route, using lanes even more tortuousa ride of it," despite the unpleasant weather conditions.expense would stand in the way.

Published about the 30th of each month by GEORGE NEWNES, LIMITED, Tower House, Southampton Street, Strand, London. "Practical Mechanics" Advice Bureau COUPON W.C.2. and Printed in England by W. Speaight & Sons. Ltd., Exmoor Street, London. W.10.Sole Agents for Australia and Thiscoupon isavailableuntilMarch31st, New Zealand -Gordon & Gotch (A/sia), Ltd. Sole Agents for South Africa -Central News Agency, Ltd. Subscription Rates (including postage) :Inland. les. 6d. per annum. Abroad, 10s, per annum. Canada, 10s. per annum. Registered at the G.P.O. 1948, and must be attached to all letters contzin. for transmission by Canadian Magazine Post. lag queries, together with 3 penny stamps.A CONDITIONS OF SALE AND SUPPLY :This periodical is sold subject to the following conditions, namely, that It shall stamped, addressed enrelope must also be enclosed. not, without the written consent of the publishers first given, be lent, re -sold, hired out or otherwise disposed of by way of Trade except at the full retail price of 9d.: And that it shall not be lent, re -sold, hired out or otherwise disposed of ina Practical Mechanics Mardi, 1948 mutilated condi tion or in any unauthorised Cover by way of Trade or affixed to or as part of any publication or advertising, 'iterary or pictorial matter whatsoever. SPARKS' DATA SHEETS A Fine Set Provide detaileddescriptivematter The verdict of many satisfied con- and Full-size Constructional Print of structors using the famous DORSET Destgns Tested and Guaranteed by Circuits. 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The youngest addition 9 -valve. med. and long. strength or weakness, and enables the to my famous range of Amplifiers. B.ATTERY FOUR. Three -wave super - A full 34 Watts Output.Vol. and Tone het.1.4or2voltvalves.(Areal most minute measurements to be gauged Controls. Good Quality.Ideal for humdinger onshort.) P.U. A.C.ID.C. 6 -valve AMPLIFIER tor accurately. Whether you are engaged in mike and pick-up, inc. pre -amp. , The above form another example of why Sparks' Data Sheets lead the way. DORSET COMPONENTS manufacturing, buying or selling, it is an They provide the designs commended speciallydesigned for above. ally of real value. No instrument you can by critical constructors and the Trade. Chassis,Coilpacks, Group Boards. I.F.Transformers. Chokes, Mains buy will more quickly justify and pay A SELECTION of my 37Designs Transformers.Speakers.etc. available' in Data Sheet form.Send Hot Spot " battery soldering outfits. Stamp for full List.Components and Send 1d. for list.Theoretical circuits, for itself. Speakers in Stock. 21d. each. THE " CHALLENGER " PORT- ABLE. An Amazing A.C.tD.C. Portable. WELDONA For the close scrutiny of every conceivable 3 -Valve plus Rect. MT, Waves. Fine RADIO ACCESSORIES LTD. object, metals, tools, fabrics, fibres, minerals, Power andQuality. NoA.orE. needed ... . 2'9 38. Gloucester Road, BRIGHTON. TWO -VA EVER (PlusRect.). preciousstones,paint,print,manuscripts, MIL' Wawa. 3} Watts Output-.2.6 A.C. THREE-VALVER (Plus Rect.). biological and botanical specimens,cutting T.R.F. Circuit. M/L, Waves...... 2i9 A.C. SUPERHET. 3Valves plus edges, fracturedsurfaces,rawmaterials, Rect. All -wave.4 Watts Output...2/6 CHEMISTRY APPARATUS A.C.8 WATT QUALITY RADIO- Send Stamp for powders,granules,and innumerable other GRAM. A.C. M, waves only.Quality rather than range. P.P. Neg. F.Bk. 3 6 COMPLETE -PRICE LIST purposes, the ULTRA LENS is invaluable, BATTERY" ALT: DRY PORTABLES. Tiny Two. Med. waves, Local station and presents in many instances hitherto un- on 21in. Speaker ._ ...2/6 Special VALVETHREE PORTABLE. Mil, Offer suspected data which can be used to advantage. Waves. A very popular Set ...2/6 THE PORTABLE FOUR. Med. Bunsen waves only. T.R.F. Circuit...... 2/6 Burnet BIOTIsii Iii Ill; FULL PARTICULARS ON REQUEST. Tripod and 11.1..NY OTHER DESIGNS for Sets Useful andAmplifiersavailable. Please include stamp with order. Prompt Glassware Service. 1216 The Ultra Lens Company, Post In id. L. ORMOND SPARKS (ND, 75, Finsbury Court, Finsbury Pavement, 9, Phoebeth/ Road, Broekley, S.E.4 Dept.A) London, E.C.2. (NearestStation : Ladywell.S.R.) BECK60(sHeln.licSTREET, ('Phone : Lee Green 0220.) Stoke Newington, London. N.16 The WINItH Geared hand wheel, with positive drive toin. MATRIC. 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Send forcopy oftheMagazine CRAFTWORKER BRITISH TUTORIAL INSTITUTE. BOOKS: (includes fullprice lists) (Dept. 1E0), 356, Oxford Street, L.N.E.R. Nameplates ... Sets of CLEAR DIAGRAMS and L.M.S. Loco Ref. Book HOMECRAFTS (Dept. 2), Albion LONDON, W.I. Planning & Layout " INSTRUCTIONS for making EASILY Street, Broadstairs, Kent. Two Rail Electrification " 3/6 WORKSHOP BENCH. SAW BENCH, L.B. & S.C.R. Locomotives... 3/6 LADDERS, STEPS. LATHE NO PASS -NO FEE" " Miniature Building Construction " 818 STANDS, WIND CHARGER MASTS LINESIDE BUILDING KITS : from " I. " section METAL (obtain- TARGET 00 0 Footbridge 2/9 - able at Zero Cost).Price 418,Posted LATHE TOOL GRINDING JIG Signal Cabin 4/- - Promptly. As advertised.-P. Robert, Loco Shed ... 7,11 - Les Buttes, Torteval, Guernsey, C.I. Shops and Flats 816. - Country Station 101- - Public House ...... 11/8 Pea Lamps. 5v. min. screw s.c. 6d. each TheInstituteofPractical_Radio Postage extra." 00 " or " 0 " Parts List Engineers have available Home Study 3d. per post. Courses covering elementary, TYLDESLEY8,HOLBROOK (II.E.T.A.) theoretical,mathematical.practical 109. DEANSGATE, MANCHESTER, 3 and laboratory tuition in radio and 114. TargetToolGrinding Jig television engineering ;the textis irises correct Lathe Tool Grinding I'ERSPEX WORKERS! suitable coaching matter for Angles,witheleas-entsharp r"Arrki,P,.:trn'orLila c "Eliminate irksome filing and turn Service entry and progressive exams. ; edges huliussihletooh fain outimproved work on yourown tuitionary fees at pre-war rates-ara Tice -hand grinding. JOINTER, and SHAPER. In one opera- moderate.The Syllabus of Instruc- tion it will make an edge dead straight tional Text may be obtained, post illustrated Leaflet) EASILY MADEFEOMOUR CASTINGS. and square. 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Air Chambers with Gauges £3 100 AlCmiulum 3 ft. a 2 ft., 12i, 6in. Saw Benches ... 210 0 0 NORWICH ENGLAND Mr 20S.W.G. Heavy Duty Jig Saws .. 0 0 Price 15:-. post free. On all above add 2d. per set. ft. carriage. Air Hose. V. Belts, Pulleys, Gauges, Valves, etc. MAINS TRANSFORMER, /1 Heats. Inquiries invited for various sections Illustrated Lists. WANTED. Loosecopies. Goodcomb. 35'-. delivered. COMPETITION CARS, LTD., The H.11.1.1.1.,2, Glamis Way, Green ford, tion. PracticalMechanics," Volume 9 HOLITOROW & CN., 71, WeVmoutb Ohl :Battings. Nayland, Nr. Colches- Middlesex. Any reasonable offer accepted.-Roberts Bay A WI) tie,Wes mon1 h. ter.Essex. : Nayland 334. 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