DO NOT CONCENTRATE ON WAR Do not concentrate your thoughts upon war subjects.You will fnd it very worrying and very bad for the nerves. Read, write, sketch, paint, study your vocation; anything that will occupy your mind and your time. Make use of the long dark nights by concentrating upon something useful. During the last war many people learned how to write short stories etc., to -day a number of them are world -famed authors. By becoming efficient in your vocation you can give the best service to your country and to yourself.The more you increase your earning power the better itis for the country and for yourself personally. War or no war, earning power always brings its possessor to the front. Itis no use waiting for better times.The ideal opportunity never arrives.We have to make the best of existing conditions.Therefore, delay is useless; it is worse, itis harmful. YOU CANNOT MAKE MONEY BY SAVING If you save 10s. per week for 10 years you have only got £260, but if you spend 2s. 6d. per week for 12 or 18 months on a correspondence course, you give your brains a chance to earn thousands of pounds, then there is no need to save.Savings are likely to vanish, but earning capacity is a permanent investment. DO ANY OF THESE SUBJECTS INTEREST YOU? Accountancy Examinations Engineering. All branches, subjectsPumps and Pumping Machinery Advertising and Sales Management and examinations Radio Communication Agriculture General Education Radio Service Engineering A.M.I. Fire E. Examinations G.P.O. Eng. Dept. Road Making and Maintenance Applied Mechanics Heating and Ventilating Salesmanship. I.S.M.A. Army Certificates Industrial Chemistry Sanitation Auctioneers and Estate Agents Institute of Housing School Attendance Officer Aviation Engineering Insurance Secretarial Exams. Banking Journalism Sheet Metal Work Blueprints Mathematics Shipbuilding Boilers Matriculation Shorthand (Pitman's, Book-keeping. Accountancy and Metallurgy Short -Story Writing Modern Business MethodsMining.All subieets Speaking in Public B.Sc. (Eng.) Mining, Electrical Engineering Structural Engineering Building. Architecture. and Clerk ofMotor Engineering Surveying Works Motor Trade Teachers of Handieratts Builders' Quantities Municipal and County Engineer Telephony and Telegraph) Cambridge Senior School Certificate Naval Architecture Television Civil Engineering Novel Writing Transport Inst. Exams. Civil Service Pattern Making Weights and Measures Inspector All Commercial Subjects Play Writing Welding Commercial Art Pollee. Special Course Wireless Telegraphy and Telephony Concrete and Structural EngineeringPreceptors, College of Works Managers Draughtsmanship.All branches Press Tool Work If you do not see your own requirements above, write to us onany subject. Full particulars free.

EVERY DEPARTMENT IS A STUDY AT HOME IN LET ME BE COMPLETE COLLEGE: EVERY YOUR SPARE TIME YOUR FATHER STUDENT ISA CLASS TO Let me tell you how HIMSELF to make a success of your career. JOURNALISM If your futureisun- Short -Story, Novel and Play decidedor appears Writing unsatisfactory,letus Thereis money and pleasure In Journalism and in Story ° r talk it over together. Writing. No apprenticeship, no pupilage, no examina- tions, no outfit necessary.Writing for newspapers, I want to help, and it novels or pictures is not a gift; it is a science that will cost you nothing can be acquired by diligent application and proper CAN YOU CHANGE MY guidance. it is the must fascinating way of making EXPRESSION ? to get my help; you pastime profitable.Trained ability only is required will be under no we do the training by poet.. Let us tell you all about it. IF SO, YOU MAY BE obligation whatever DEPARTMENT OF LITERATURE 76 THE ARTIST THAT COMMERCE IS WAIT- I( you attend to this now, it may make ING FOR I HAVE HELPED THOUSANDS a wonderful difference to your future. Just tryItfor yourself. OF OTHERS car,Trace or draw the outline COUPON- so- and then put in the features And when I say thousands. I do not exaggerate, CUT THIS OUT There are hundreds of openings in connection with asI can produce well over 10,000 unsolicited w Humorous Papers, Advertisement Drawing, ww - - gratefulstudentswho. To Dept. 76, THE BENNETT Posters, Calendars, Catalogues, Textile Designs, testimonialsfrom COLLEGE LTD., SHEFFIELD Book Illustrations, etc. through our Postal Train- Please send me (free of charge] 60 per cent. of Commercial Art Work is done by " Free Lance Artists " who do their work at ing, have achieved their Particulars 01 home and sell It to the highest bidders. Many Your private advice about Commercial Artists draw " retaining fees " from life's ambition (Cross out line which does not apply, various sources, others prefer to work full-time employment or partnership arrangement. We teach you not only how to draw what it wanted, but how to make buyers want what you draw. Many of our students who originally took up Commercial Art as a hobby have since turned It Into a full-time paying profession with studio and staff of assistant artists; there Is no limit to PLEASE WRITE IN BLOCK LETTERS the possibilities. Let us send full particulars for a FREE TRIAL and details of our course for your Name inspection. You will be under no obligation Address whatever. - c/t'"1- c -I ART DEPT. 76. Dept. 76, THE BENNETT COLLEGE, SHEFFIELD

II December, 1939 NEWNES PRACTICAL MECHANICS 97

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ZZ7 figlinanagramawsllyzez------RAWLPLUG RAWLPLUGS It's so easy to make neat permanent fixtures UROF1X with Rawlplugs-without damage to walls or decorations.Every Rawlplug Outfit contains RAWLPLUG DUROFIX full equipment for fixing any ordinary article Durofix resists heat and water, and is readyto any material.A Rawlplug Outfitisin- for instant use without first warming as isdispensable to every householder who takes a necessary with most cements. It is colourless, and joins made with Durofix are almost in-pride in his home. Complete outfits, 1,6, 3,6 visible.There are hundreds of usesforor 5/6. Durofix in every home. Sold in tubes at 6d. and 1 /- each. RAWLPLUG PLASTIC WOOD Rawlplug Plastic Wood isRAWLPLUG TILE DRILLS apliable material whichThe Rawlplug Tile Drill is a twist drill of very high PIA STIC 'JUNIOR' can be moulded andquality.It can be used for drilling hots in tiles,ELECTRIC ;WOOD, brick and soft stone, and can be re -sharpened very ,n,dly rdnf; fashioned into any shape DRILL and Very quiet and outstandingly efficient in use. =(an desired. Hardens wheneasily. A practical electric hand Prices from 9d. to 1 /9 each.Sizes from -it" to r. 'h:ZgoT:';0 dry and becomes exactly drill for the handyman's (14 nails and tnyalala, workshop. Sturdy, light Wr* ad like real wood, when it can and dependable, n :ianrho. RAWLPLUG BLOW LAMPS it en- 4nY floors 6,1, be cut, stained, planed or suresaccuratedrilling. F;74LL'gueT The Rawlplug Spirit Blow Lamp is an efficient lampDrillswood ormetal. end Qaid painted.Waterproof and house Eiold use for all soldering work. Can be used for heating andTakes up to+"drills. weatherproof. Tubesattinning the soldering iron and for "sweating" joints.Can also be used for 6d. and 1/- and in tinsA very useful lamp for all general heating purposes.sandpapering, buffing, from 9d. upwards. burnishing, etc. All Price 1 6 each. voltages. Price42:-each. TheRawlplugCo.,Ltd.,RawlplugHouse,CromwellRoad,London,S.W.7

ebri5tma5 r e5ent5 Deciding Factors. How about a Model Train, Boat or Aeroplane ? Or if you would like to build something we can supply all types of fittings, castings, materials and tcols. The DLP Vice -Screwing Machine should occupy a Send 6d. for Bond's 208 -page catalogue which illustrates and lists all the central position in YOUR workshop. items that we can supply. Parallel Vice Pipe Vice "Endeavour" Yachts Adaptability Tube,RodandStrip Bender Megow The DLP Machine Cable,Rod andPin combinesthefunc- Cutter tions of all these tools, Screwing Machine Balsa Flying Kits without loss of indi- Punching Machine vidual efficiency. Cable Stripper Flat and Conical Anvils The space required on your Compactness bench isonlyl2" x 18% The purchase priceis but a fractionofthecostofthe Economy separate tools listed above.

KitsforI2 -in. wing spanFlying Models of the AERONCA, BOEING £5-17-6 PI2E, CURTISS PURSUIT, HELL Illustrated DIVER, LOCKHEED VEGA, Folder MONOCOUPE, PUSS MOTH, on Application. STINSON RELIANT, TAYLOR CUB, VULTEE VIA, WACO, CURTISS FALCON, SPAD, SOP - WITH CAMEL, NIEUPORT, GULF HAWK, HORNET MOTH, MILES MAGISTER. These new Yachts are the latest thing for fast PriceI Id.Postage 3d. racing work. All of the hulls are hand made in best yellow pine.Cabin skylight extra. Kitsfor 24 -in. wing spanFlying Patent No. Models of the STINSON RELIANT, 418,829 Prices: WACO CUSTOM, MONOCOUPE, 17 -in. Yacht with automatic rudder 13/2 CONSOLIDATED P/30, FAIR- 21 -in. Yachwith automatic rudder ...20/4 CHILD, HAWKER FIGHTER, 27 -in. Yacht with Braine type steering 43/S CURTISS HAWK, RICHMAN and 36 -in. Yacht with Braine type steering 82/6. MERRILL'S VULTEE. Price2/6. Carriage extra. Postage 4d. SOLE DISTRIBUTORS FOR THE BRITISH ISLES BOND'S EUSTON ROAD LTD. BUCK&HICKMAN LTD. 2 WHITECHAPEL RD., LONDON, E.I. 357, Euston Road, London, N.W.I Overseas Enquiriesto DeLaPre Components Ltd., Northampton Telephone: EUSton 5441-2. Est.1887. g52.46 8 NEWNES PRACTICAL MECHANICS December, 1939 [-ENGINEERS EQUIP YOURSELF FOR WORK OF NATIONAL IMPORTANCE BY BECOMING TECHNICALLY QUALIFIED Men with technical knowledge are as important as troops and ammunition.For the country's immediate needs and your own future gain you are urged to send immediately for afree copy of "ENGINEERING OPPORTUNITIES." Containing 268 pages of practical guid- ance, this bookis, beyond argument, the finest and most complete handbook on Successful Engineering Careers ever com- piled.It is a book that should be on the bookshelf of every person interested in engineering, whatever his age, position or experience. The Handbook contains, among other intenselyinterestingmatter,detailsof B.Sc.,A.M.I.C.E., A.M.I.Mech.E., A.M.I.E.E., A.M.I.A.E., A.M.I.W.T., A.M.I.R.E.,CivilService and other important Engineering Examinations; out- , lines courses inall branches of Civil, Mechanical,Electrical,Automobile, Radio,TelevisionandAeronautical Engineering,Building,Government Employment,etc., andexplainsthe unique advantages of our Employment Department. WE DEFINITELY GUARANTEE " NO PASS -NO FEE " If you are earning less than per --TEAR 0 FF HERt week you cannot afford to miss reading "ENGINEERING OPPORTUNITIES." In your own interests we advise you to write (or forward the coupOn) for your copy BRITISH INSTITUTE OF of this enlightening guide to well -paid posts I ENGINEERING TECHNOLOGY, -NOW. I 410a, ShakespeareHouse, 17-19Stratford Place, W.1. There is no coil or obligation of any kind. I Pleaseforward,Freeof costor obligation of anykind, your BRITISH INSTITUTE OF I 268 -page Handbook "ENGINEERING OPPORTUNITIES," I Name I ENGINEERING TECHNOLOGY Address

410a, SHAKESPEARE HOUSE, I 17,18 & 19, STRATFORD PLACE, LONDON,W.1 I VERN December, 1939 NEWNES PRACTICAL MECHANICS 99

SUBSCRIPTION RATES Inland and Abroad 7s.6d. per annum Canada - - 7s. per annum PRACTICAL Editorial and Advertisement Offices:" Practical Mechanics," George Newnes Ltd. Tower House, Southampton Street, Strand, W.C.2. 'Phone: Temple Bar 4363. Telegrams: Newnes, Rand, London. Registeredatthe G.P.O.for transmission by Canadian Magazine Post. MECHANICS Copyright in all drawings, photographs, and articles published in "Practical Mechanics" Editor:F. J. CAMM isspecificallyreservedthroughoutthe countries signatory to the Berne Convention and the U.S.A. Reproductions or imitations of any of these are therefore expressly forbidden. VOL. VII.DECEMBER, 1939.No. 75 FAIR COMMENT

Will you Help? because wood pulp forms one of theminingdistrictsanddistributethe ingredients of munitions.Additionally,power throughout the country. VERY reader of this journal is byit is exceedingly difficult now to import As far as the overhead -grid system is all Enow aware of thefact that paper and the raw materials used inconcerned,I newspapers, and some periodicals, are regarded it with mixed its manufacture. feelings when it was first mooted.I available only to standing order. News- Readers, therefore, will be perform-pointed out, in the Press and elsewhere, agents in many cases are not permitteding a service which we shall greatlythat in time of war it would provide the to return unsold copies, and whilstappreciate if they will at once place aenemy with a means of locating every many of them have the wisdom to orderstanding order with their newsagentspower station in the country, as well as extra copies so that they can still supplyfor the regular supply of this journal,providing him with an aerial map of casual sales and thus take the risk ofand thus help us to conserve our paperGreat Britain. Unfortunately, my words having a few unsold copies on theirsupplies. It is important that we shouldwere not heeded, for the scheme was hands, some are adopting the practicenot waste the paper used in the produc-planned soon after the last war closed, oforderingonlysuchcopiesastion of unsold copies.In normal timeswhen peace and disarmament were in willmeet their certain requirements.we are happy to supply newsagents withthe air and politicians were paying lip DuringthepastmonthIhavea sufficient number of copies to supplyservice to peace in our time.I am quite received a large number of complaintsall needs and we permit them to returncertain now that those responsible see from readers who, accustomed to pur-unsold copies. Now that we have beenthe error of placing cables overhead. chase their copies from different news-compelled to economise in this directionIt has advantages if the world can be agents, have found that they have beenthe reader in helping us in the mannerkept at peace.Unfortunately, we now unable to purchase a copy. There havesuggested will be helping himself andknow that war is one of those inevitable been cases of other readers who havealso the State. andrecurringdisasters which over- placed a standing order but have still I drew the reader's attention to thistake the world at least once every 25 been unable to obtain the copies becausematter last month, but there are manyyears. an assistant behind the counter, unawarewho did not heed my advice.I hope, When this present war is over I hope that copies in stock are on order, hasnow that I have stressed the point, thatthat due consideration will be Riven to supplied casual sales and then evenit will not be necessary for me to havethe economical production of cheap regular readers have been unable toto answer further letters explaining whypower andamodificationofthe obtain copies. We hope our readerscopies have not been so readily availablegrid scheme on the linesIhave sug- will co-operate with us by sending usfor casual sales. gested. detailsofallsuch cases.Where a reader has had the wisdom and foresightPower from the Pithead Our Workshop Series to place a standing order, it is unfair COAL is one of the vital minerals of THIS month I commence the first of that his copy should be sold to a casual industry. Upon itsproduction a series of practical articles intended customer. We are,ofcourse, en- deavouring to supply each newsagentdepends the generation of millions offor all those thousands of readers who with an adequate supply, of copies tohorse -power per year for the operationare now engaged in the workshops of meet all demands. of power plants, locomotives, ships, andthis country.The series will cover steam -driven machinery,quiteapartevery aspect of engineering, from the from its use as a fuel for heating pur-foundry to the finished product, and the Cost of Paper Increased poses. It has always seemed to meworkshop processes to be dealt with will WE are doing our utmost to ensurefutile to mine the coal and to dispatchinclude tool making, fitting,turning, the widest possible distributionit all over the country, thus adding topattern making, milling, planing, shap- throughout the war, which brings in-.itscost, when the power itself coulding,boring, works layout,precision evitable problems to journals of thisquite easily be produced at the pithead,grinding,forging,presstoolwork, character.On the cost side alone, thewhere the coalis cheapest, and thefinishing, polishing, plating, sheet metal paper on which this journal is printedpower distributed through the countrywork, and plastics. has risen by as much as 60 per cent.,by means of the grid scheme.This Each process will be dealt with by and there are indications that priceslatter links up the various electricalan expert in that particular field, and will rise even beyond that figure.Theundertakings of the country, whereas bythe series will be illustrated by practical Government iscontrolling the paperthe pithead production of poweritdrawings and photographs.A further output and rigidly rationing suppliescould be used merely to link up thearticle will appear next month. 100 NEWNES PRACTICAL MECHANICS December, 1939 Easy Magic For Christmas Mystifying Tricks that Need Neither Skill nor Special Apparatus

Nornian Hunter (TheIre11-known Cov'urer of " Maskelyne's IllYsteries") Further Articles on the Secrets of Conjuring will appear Regularly and Exclusively in this journal

appear to be quite clean as the white enamelled surface of the disc hides the writing.The plat( s are now smoked over by allowing the flame of a wax taper to play on the surface of the plate. Move the taper about so that no part of the plate gets too hot.In smoking the plate with the disc Fig. 3.-The overflowing bowl.How the silk Fig. I. -A trick with smoke.The painted metal on it, the disc is held in position by pressure disc is white on the reverse side and covers the of the fingers, and itis the disc which scarves are concealed in the space below the false prepared letters on the ready smoked plate receives the sooty deposit. Wipe round the bottom of the bran bag THE conjurer shows two white chinaedges, and in doing so clean away all theshows his right hand empty.By passing plates and proceedsto blacken thesoot from the faked plate, leaving only thehis hand in front of the box he causes the insides by smoking them with a burn-disc sooty. matchbox label to change to an entirely ing taper.He carefully wipes the edges The unprepared plate is now placed overdifferentone. Anotherpassproduces clean, leaving a black disc the other and the two reversed in placinganother change, the right hand being shown of each plate and places the plates together.them on a side table. When they are againempty each time and the back and front one upside clown on the other. separated the paintedsideof the discof the matchbox being also shown each time. He now asks members of the audiencerepresents the smoked part of one plate,Finally, a third change takes place and to name various towns in England.Onewhile the prepared word stands out in thethe box is thrown out for inspection. of these is chosen and when the plates aresooty deposit on the other. The box is not prepared. With it is used separated the name of the chosen town To ensure that the right name is chosena fake consisting of a piece of cardboard is seen printed on the soot -covered surfaceis simple.As the names are called out youcut to the size of the front of the box. A of one plate.To prove that the printingwrite the same one down each time on slips of paper.The slips are then folded and OTHER SCARVES LABEL 't dropped into a hat from which a member of the audience is asked to take one.As all slips hear the same name, he cannot fail to choose the word the conjurer has prepared. Camouflaging a Matchbox The performer shows an ordinary box of matches.He holds it in his left hand and

SQUARE SCARF PAPER PASTED ROUND BOX TO FORM BiNG BULLDOG CLIP FOLD IN Fig. 2.-Camouflaging a matchbox CORNERS OTHER OF SCARF has genuinely been done by wiping the SCARVES letters out of the soot, the performer takeS a cloth and rubs the whole of the black off the plate. LOAD OF Fig. 1 shows practically the whole of the SCARVES secret.The plates are not prepared, but with them is used a disc of tin enamelled (ED white on both sides.One side of the disc Fig. 5.-The load for the overflowing bowl is now painted withflatblack,leaving abotit half an inch margin round. The disc different matchbox label is pasted on each fits neatly into either plate. side of this fake.The ordinary box should be one of the kind that has a label on both Preparing the Trick sides (Fig. 2). To prepare the trick, carefully smoke one At. the start the fake is underneath the plate with a wax taper and wipe round the box.Both hands are shown empty except edge so as to leave a neat black disc in the for the box, but the reverse side of the box centre of the plate.With one fmger print, CARDBOARD BOX is not shown.In making the first change by wiping away the soot, the name of a town UPSIDE DOWN the box is -simply turned over under the as shown in the photograph.Place the tin cover of the right hand.This exposes one disc on this plate, black side down.The Fig. 4.-The overflowing bowl.The. fake hag is side of the fake.The second change is two plates may now he shown and will made by pasting brown paper round a cardboard box made by turning the fake over on time box December, 1939 NEWNES PRACTICAL MECHANICS 101 bowl and over the load.If desired thestretched hand. The handkerchief lies quite bowl of bran may be tipped forward andflat over the palm of his hand.With the shown.The production then proceeds byother hand he picks up the handkerchief by simply releasing the clip and drawing outthe centre and slowly liftsit. revealing a the silks. wineglass standing on the palm of his hand. Kings' Congress This is quite easy, but if neatly perfortntittl the effectis a small sensation. IThe a This is a card trick.The four kings arehandkerchief or scarf about two feet square. taken from the pack.Two are placedThe wineglass is concealed under the left respectively on the top and bottom of thearm under the pack ;the remaining two are put in the jacket,the bowl being CUTTING PACK BY gripped under the armpit and the foot LIFTING OUT BOTTOM centre.Yet when the conjurer deals out HALF INSTEAD OF TOP the cards all four kings have come togethersloping down and forwards.Hold the in the centre, of the pack. scarf four square to the audience with the No preparation and no special cards arethumbs on top and all the fingers behind. needed.After placing one king at theThe backs of the hands will be turned bottom of the pack and one at the top youtowards the audience. say that you will cut the pack.This you Having shown one side of the scarf, pass do.But instead of lifting off the top halfthe right hand behind the left, bringing the to make the cut, you slide cst the bottomleft hand across to the right side.This half.Fig, 6 shows you how to do this.shows the back of the scarf and brings the When the remaining two kings are placedright hand naturally insidethejacket. Fig. 6.-Method of cutting the cards for the kings' between the two halves, they naturallyTake hold of the stem of the wineglass congress trick go on top of the king already on top of thebetween the first and second fingers, the pack.Similarly the king which is on the.foot of the glass resting against the inside as the hand passes across it.The third of the fingers. change is accomplished by again turning the Bring the hands back to the original box over, thus bringing the original label position and the glass will remain hidden into view.The loose fake is then slid off behind the scarf. Now hold the right hand and concealed in the bend of the fingers palm upwards, quite flat and drape the while the box is thrown fdr inspection. scarf over it, taking care not to expose While the audience are busy looking for the glass as you do so.The position is now spring flaps,the conjurer quietly drops the as shown in Fig. 7. fake behind some article on his table as he To produce the glass, nip the scarf just picks up some object for the next trick. on the palm of the hand and raise it straight Now for a showy trick: up. As you do so, under cover of the folds, bend the fingers of the right hand over until The Overflowing Bowl WINE GLASS the glass stands on the palm of the hand. The bowl is an ordinary one of brass or SUSPENDED See Fig. 8.All that remains to be done papier miche, and it is shown to be quite FROM FINGERS is to release the grip and straighten the empty. Bran is poured from a bag' into the fingers, which leaves the glass standing bowl, and the pouring is done from sufficient on the outstretched hand as the cloth height to prove that nothing is introduced is lifted right away. with the bran.Yet, in spite of this, the If you possess a rubber cover to fit the conjurer plunges his hands into the bowl glass (you can buy these covers from shops and produces from the bran numbers of silk scarves or flags. Fig. 7.-How the wineglass is held in the fingers The secret in this case lies in the bag. under cover of the cloth This has a false bottom placed some waybottom of the pack comes on top of the other up inside the bag, and it is in the space sothree when the halves of the pack are placed formed under the bag that the load oftogether. scarves is concealed, as shown in Fig. 3. The best way to finish the trick The easiest way to make the fake bag isis to spread the cards out face upwards to take a cardboard box of suitable dimen-on the table with a sweeping movement. sions and paste stout brown paper round itA Wineglass from Nowhere as shown in Fig. 4.Crease the corners The performer shows a large handkerchief down and trim the paper level with the rimon both sides and spreads it over his out - of the box at the bottom, or else turn the edge of the paper in and paste it down. The load of scarves is now prepared as shown in Fig. 5.A large square scarf is spread out and the remaining scarves, or any other articles it is desired to produce are placed in the centre of the square. The corners are now turned in and the folded corners so formed are turned in again, until the bundle is small enough to slip easily into the space under the bag.An ordinary bulldog clipis then used to fasten the corners together.Fig. 5 A shows the first stage of this preparation and B the finished parcel.In Fig. 3 the scarves are shown loose in the fake bag for the sake of explain. ing the general idea.Actually, however, the load must be done up tightly so as to Fig. 9.-Vice versa.The wineglass being inverted drop out of its own accord. under the covering cloth, allowing the egg to drop into the hand Performing the Trick To perform the trick, have some loose which sell conjuring tricks) you can produce bran in the upper part of the bag. Show the the glass full of wine, the rubber cover bowl, which should be large and deep. keeping the liquid in.In this case the Put the bag of bran bodily inside, keeping cover is pulled off in the folds of the scarf. one hand under the bag as you lift it to prevent the load from falling out.Take a Vice Versa handful of bran from the bag and trickle An egg isplaced in a wineglass and it on to a plate to show what it is, then covered with a cloth. A small silk hand- lift the bag out of the bowl, holding it by Fig. 8.-Producing a wineglass.Here the glass kerchief is rolled between the hands and the top edge. This will leave the load behind is being brought up to stand on the outstretched it changes to the egg.When the glass is in the bowl.Bran is now poured into the hand under cover of the cloth uncovered the handkerchief is found inside. 102 NEWNES PRACTICAL MECHANICS December, 1939

5.ALLE0 pretend to put the sixpence into the closedwhich suspends the flowers.(See Fig. 11.) HANDKERCHIEF left hand. Slip the double loop off the nail in the table You can now lay great stress upon theand over the nail in the frame. The double fact that with your wrist held by two peopleloop makes this easy because you simply you cannot possibly get the sixpence out oftake hold of the top loop and lift it over the your left hand undetected.Quite true.nail on the frame, which automatically But as the sixpence has never been in thefrees it from the nailin the table.The left hand, its disappearance is now quite easy. The Picture Comes to Life BETWEEN HANDS A plain wooden frame is freely shown and a sheet of paper is stretched over it, being fastened down with drawing pins. Both sides of the frame and paper are shown Fig. 10.-The balled handkerchief is held at the and the conjurer then picks up the frame finger tips whilst the egg remains hidden between and draws upon it a sketch of a bunch the palms of flowers. Having finished the sketch, he breaks the As only one egg and one handkerchiefpaper, puts his hand through the picture are used inthis trick, the egg may beand produces from the empty frame a bunch marked and the handkerchief borrowed.of flowers similar to the sketch, thus making thus adding to the effect. the picture come to life. PAPER Fig. 9 shows the move upon which the This trick is very simple and easy to do PINNED TO whole secret depends.Choose a wineglassin spite of its brilliant effect.The frame is rRAME of the port type which has an open bowl. FLOWERS SUSPENDED The foot of the glass is approximately the NAIL IN FRAME BEHIND FRAME same diameter as the rim.Take the egg HEADLESS, ( use a hard-boiled one or a wooden one for ,NAIL safety) and get someonetoinitialit. Hold the glass Fig.I2.-Laythe frame flat and pick it up again Drop the egg into the glass. by the top.This will cause the bunch of flowers by the bowl and throw the cloth over it. DOUBLE to come up and hang behind the frame As the cloth covers the glass, quickly turn WIRE the glass upside down as shown in Fig. 9. The foot of the glass now shapes the draped movement is covered by the other hand cloth and to the audience it looks exactly picking up a large sheet of paper. the same as if the glass was right way up. Pin the paper to the frame with drawing 'rake the covered glass with the right hand pins. Now lift the bottom edge of the fraine, and stand it on the table.The egg drops which is nearest to the audience as the frame out and remains concealed in the slightly lies on the table.This permits the audience curled fingers of the right hand. to see the back of the paper. Lay the frame flat and pick it up again by the top.This Concealing the Handkerchief will cause the bunch of flowers to come up The borrowed handkerchief should be on and hang behind the frame as in Fig. 12. a table to your left.Pick it up with the Fig. 11.-A bunch of flowers suspended behind Sketching the Picture hand that holds the egg.Roll the handker- the table by means of a loop of florist's wire chief into a ball, then conceal the balled To sketch the picture use either very soft handkerchief behind the fingers and bringjust an ordinary wooden picture framepastel chalks or else a small paintbrush and the egg into view instead.The simplestwithout glass or back.In the centre of thea bottle of black ink.To make sure of way to do this is to hold your hands as iftop a small nail is driven. getting a reasonable looking sketch quickly you were saying a prayer that the trick The bunch of flowers, which can be realyou can draw it out on the paper before the will come off all right.Hold the balledor artificial, just as you like, is suspendedshow, using very pale yellow chalk or pencil. handkerchief at the finger tips, the eggbehind the table by a loop of florist's wireThe outline will not be visible to the audi- remaining hidden between the palms (seeas shown in Fig. 11.The wire goes roundence, but you will be able to see it clearly Fig. 10).The fingers now draw back thethe stems of the flowers and is then twistedenough to follow with your brush and ink. handkerchief while the thumbs rolltheinto a double loop; one loop being above When the sketchiscomplete,break egg up and over it. the other.The lower of the two loops isthrough the paper, unhook the flowers and Take the egg in the left hand and giveslipped over the nail, which should havepull them through the torn sketch.The it for identification.Pick up the coveredthe head cut off.The cloth on the tableframe and paper canagain, he shown wineglass by the foot.Place the righthides the flowers from the audience. on both sides. hand under the folds of the cloth and tuck One final word of advice. Do not attempt the handkerchief into the inverted glass.Preparing the Frame - any of these tricks, simple though they are, Grip the bowl of the glass between fore- In performing the trick, show the framein front of an audience without trying them finger and thumb.Let the glass swingfreely but keep a finger over the nail soover once or twice in private.It is fatally round to its normal position as you removethat it is not seen.Place the frame on theeasy to fumble even the simplest action if the cloth. table with the nail towards the loop of wireyou haven't done it before. Melting Money The conjurer says he wants a small coin for the trick. He finds sixpence among the other coins in his pocket and, returning A Novel Soldering -iron let the other coins to his pocket, deliberatelyIFyou do a great deal of constructionalring proves too expensive, and the illustra- puts the sixpence into his left hand, which work inradio anduse an ordinarytion depicts a method adopted for introduc- he closes. He now gets two members of thesoldering iron, the use of the kitchen gasing the element of economy. audience to hold his left wrist.Yet when The mounting base is made of 14 gauge he opens his hand the sixpence has gone. aluminium, being fashioned at the jet end, Although this is a rather dishonest sort although this is not absolutely essential. of trick, itis extremely puzzling.When The jet is provided by clipping the pilot .you find the sixpence among the other coins flint jet normally supplied with a certain you hold it up between thumb and forefinger type of popular gas stove into small brass with the remaining coins still in the hand. spring clips, as shown ; then, by regulation Say " We shan't want the other coins," at the stove, any heat intensity can be plunge the hand into your pocket and leave obtained, preventing the iron from either -A- BRASS CURS the coins there. Now comes the crafty part. . cooling off or over -heating. - In leaving the loose coins in your pocket 11A CASHA Theironsupportsareprovidedby JET RE nous you also leave the sixpence there and bring A7 STOVE turning up one end of the aluminium, whilst your hand out empty but still held as if it iCO.244° fashioning one other bracket piece which is had the sixpence between thumb and finger. screwed to the base with 4BA bolts as for Keep the hand moving and very deliberately Details of the device the spring clips. December, 1939 NEWNES PRACTICAL MECHANICS 103 BROADCASTING YOUR OWN PROGRAMMES

How to Connect and Use the Gramophone with any Existing Receiver, and suggestions for Increasing the Entertainment provided by plug to which the pick-up may be join- Gramophone Records with various Devices ed, and this plug is inserted into the valve -holder beneath the valve. That THERE are occasions when the broad- is'to say, the valve is pulled out of its cast material does not provide the holder in the set, the plug inserted in necessary entertainment, and in the its place, and then the valve is put ordinary way this would mean that at a back on top of the plug. The pick-up party or family gathering a sudden lull is then in position aad may be used in descends upon the proceedings. The usual the usual way. From what has been problem then arises as to what to do next. said previously, it is obvious that an Some would like to play games, others want H.F. valve must not be removed, and to do something else, and so on.Where,at high frequency.Therefore, the high -thus the pick-up plug or adapter is inserted however, a gramophone pick-up is fitted asfrequency, portion of the receiver is out ofonly in the detector or L.F. valve -holders. If part of the radio equipment no such problemaction when a pick-up is being used, andthere is no volume control on the L.F. side can arise, as the vast variety of gramophonealthough you can use the detector valve inof the receiver it may be found with some records which is available will enable anyaddition to your L.F. stages, you cannotpick-ups that overloading and consequent desired programme to be given to youremploy the reaction control. The pick-updistortion will take place if the pick-up is guests. You can have any of your favourite used with the detector valve, due to the radio fact that the amplification is too great to stars,instrumentalists,ordance enable the output valve to handle the signal. bands, and there is no need for any dull In such a case the pick-up would be joined moment when you possess a radiogram. Fig.1.-This adapterto the L.F. valve. Contrary totheviews held by many enables thepick-upto listeners, it is not necessary to have access to be used with any Choosing a Pick-up the electric -supply mains before you can receiverwhichisnot When obtaining your pick-up, therefore, use a radiogram.Although the majority already provided withyou must first consider your circuit.If of radiograms onthemarket are designed Dick -up terminalsorthere is only one L.F. stage, you can only for mains operation this does not indicate sockets use the detector with that stage and this that mains are essential, and this point will provide quite a good degree of ampli- seems to have prevented many listeners fication.Consequently you should obtain from obtaining a pick-up and converting a pick-up with a moderate voltage output. their receiver into a radiogram. Provided Similarly if your receiver employs a metal that the -volume delivered by your receivermay be used with any receiver without therectifier feeding the output stage, you can on the radio programmes is ample for yourneed for breaking or disconnecting a singleonly use one stage of L.F. amplification, normal listening needs without the necessitywire, and it is possible to purchase a specialand a very sensitive pick-up would be needed to obtain sufficient volume. Yau can obtain a pick-up for as low as 5s., or if you have no portable gramophone with which to use this simple type of instrument, you may obtain one complete with a carrier arm. As a motor has to be used to turn the record, however, a simple portable gramo- phone of the standard type may be obtained quite cheaply and will enable you to make your receiverinto a radiogram at the minimum of expense. If you desire to re- design your present receiver to make it into one of the modern types of radiogram, you can obtain a clockwork or electric motor to mount on the top of the cabinet, and fit a standard pick-up with arm and volume control.In this case the makers will supply a template showing the correct position for the carrier arm to ensure that the tracking is correct. That is to say, if not correctly mounted, the angle of the needle in respect to the sound grooves on the record will change and this inay result Fig. 2.-The method of connecting a pick-up in the records being damaged owing to the permanently to a battery detector stage. sides being scraped. The position varies according to the type of pick-up and, there- for using excessive, reaction, then you can fore, you should follow the makers' instruc- obtain a similar volume from a gramophone tions on this particular point. pick-up. Correct Motor Speed Fitting a Pick-up If you use a clockwork motor, or an To explain the last pointit may be electric one with speed control, you will mentioned, for those who are not familiar only obtain the correct musical pitch when with the subject, that the gramophone the turntable turns at the correct speed. pick-up operates at low frequency, or audio With themajorityof modern records frequency, and the reaction control operates this speed is seventy-eight revolutions per 104 NEWNES PRACTICAL MECHANICS December, 1939

ADDITIONAL SPiNDLtMOUNTED ON MOTOR - edge of the turntable. (Fig. 3.) Alternatively, BOARD OR I/Et° /N NAND you can hold the record on a pencil or similar ORD/N.4,01' 7i/RisitTASLE round object,resting the under surface on your thumb, and can then press the edge of the turntable giving the required pressuretopreventtherecordfrom slipping. A Permanent Connection If you require the pick-up to be a per- manent connection, a simple single -pole change -over switch may be fitted as shown in Fig.2.The grid condenser and grid leak are disconnected from the grid ter- minal of the valvebolder and are connected Fig. 3.-By playing a record bacltwards as shown here, you can obtain some very weird effects to one side of the change -over switch. The grid is joined to the arm of the switch, minute, and if the speed regulator is marked and the other side of the switch is joined in revolutions per minute itis a simple //04.E DR/LLED ECCENTRICALLY to the grid bias battery.If the receiver matter to set the indicator to the correct is of the mains type the grid -bias connection position.If no indicationisprovided is ignored, and that side of the switch is or you wish to check the speed you can use joined direct to earth. To provide the bias a stroboscope (provided you have A.C. for the detector valve (which, you will lighting mains available). This consists of a remember,isnot operating as an L.F. disc having black and white markings round valve), a suitable resistor is joined in the the edge and these are in such a position cathode lead and by-passed by a suitable that when the disc rotates at the correct condenser.The grid leak is then joined speed, and itis viewed in the light from direct to the cathode. The arrangement is an ordinary 50 -cycle A.C. lighting supply shown in Fig. 5, and in the majority of the markings appear to remain stationary. cases a resistor of 1,000 ohms would be If the motor runs slowly the pitch of the needed for the bias circuit and a 25-mfd. music will fall and you can add to the Fig. 4.-Adding to the fun by playing a record electrolytic condenser may be used for amusement of your guests by playing a eccentrically by-pass purposes. record at half -speed.It is interesting to note the effect of this arrangement, as the instruments which have few harmonics (such as the saxophone, trumpet,etc.) do not sound much altered, but the piano, which is rich in harmonics, has a most weird tone and you will find that many peoplecannotidentifyitasapiano. Similarly, by running at a very high speed the pitch is raised and the human voice becomes very squeaky, producing an effect similar to the old-fashioned gramophone, owing to the apparent elimination of the lower frequencies. A further scheme to add to the liveliness of a party is to play records backwards, or by the use of an eccentric hole. For the latter another hole should be drilled (or burnt with the aid of a cigarette end) about i in. from the correct hole.As the record then rotates eccen- trically it is not possible to startit, and then place the needle on the groove. The needle,must,therefore,be placedinto position first, and the motor started up, spinning the record so as to obtain the correct speed as soon as possible.(Fig. 4.) 1111 To play a record backwards, a separate spindle should be mounted on the motor - board, and the record may then be placed on this with its edge resting against the Fig. 5.-Fitting the pick-up to a detector tage in a mains receiver

slowlyduring an electricalstorm, and Rare Non-Metalic Element finally bursts-without as far as is known, iodineisan essentialof NOTES AND NEWS doing any harm.As, however,it never ALTHOUGHhuman life, it is one of the rarest non- leaves anything behind to investigate, it is metallic elements.Less than one -fiftieth impossible to say with certainty of what of a gram is contained in a ton of sea wa ter,becoming an actual fact, and that pioneersit consists. and although iodine is scattered about the" intend to land on the night side of the earth in minute quantities, there is only onemoon as the sunlit sideis hotter thanHeaven in Fourth place in the world-Chili-where it existsboiling water and they did not want to go in sufficient concentration to be workable.looking for trouble until they were ready Dimension for it." SIR AMBROSE FLEMING recently Trip to the Moon made the suggestion that Heaven may to the present war, the British be in the fourth dimension. He states that ()WINGInterplanetary Society have ceasedA Thunderbolt although it is the custom to speak of the all their official activities and the Society's ALTHOUGH ',there are people who stateabode called Heaven as if it was some region records have been placed in safe custody that they have seen a thunderboltinour spaceof three dimensions, yet for the duration. A space ship had beenfall, scientists have now decided that therescientific analysis has shown that our space built in theory for a projected trip to theis no such thing as a thunderbolt. Theymay be only, as it were, one section of a moon, and at the outbreak of the war theadmit a rare and strange phenomenonlargerfour-dimensionalspace-timecon- Society were mainly engaged in designing aknownasballlightning-aluminous,tinuum, and that passage from One to the speedometer for the ship.It was claimedcircular body which descends to earth orother is by a movement in a fourth dimen- that a trip to the moon was on the way totravels along the ground comparativelysion. December, 1939 NEWNES F'KAC I ICAL MECHANICS 105 A Model Of John Cabot's ShiP OldTimeShipsMakePicturesque Models.The Model Described Below Measures 12 in. in Length and is made on the Solid Hull Principle

shown in figure 8The top and the inner side facing the keel and the use ofshould be marked. Otherwise the cutting these makes theof the shape will remove the pencil lines. construction Begin by cutting the plan shape straight simple sinceitdown at right angles. Much can be sawn is only necessaryaway, the -chisel being used afterwards to to scale the partsremove the lumps. A spokeshave or file to obtain the shapes.The detailis used to finish off. The elevation shaping given represents the minimum thatfollows, this again being taken straight should be put in to give good effect.across at right angles. The resulting shape A great deal of extra rigging and deckis shown at the top in Fig. 3.It is square fittings can be added with advan-in section and needs to be rounded. tage. There are many pictures and As the fullest part of the hull is amid- models in libraries and museums fromships, this shape can be cut first, and a which these can be taken. reverse template of it should be cut in cardboard. The Hull The stern view to the left Fig. I.-The finished model in the design shows it. The wood should be of John Cabot's ship This consistsinthe main of afixed in the vice or held down with a centre keel, A, with the shaped hullscramp and the waste chiselled away.Be LITTLE is known of the details of the careful not to remove too much, and place actualship Cabotsailed the template frequently against the hull from Bristol in 1479, and in attempt- to see just where the wood needs removing. ing to reconstruct it in model form the Having made the centre approximately best plan is to design it on the lines of a correct, work first towards the stern and typical late 15th century ship.The general then the bow, making the shape to sweep form and details of this can be gathered in a fine curve. After chiselling, a block from old pictures and records which have plane or bullnose plane can be used with survived. Ships of this time were extreme- advantage. Following this a file is run over ly picturesque, though, judged by later the whole thing With a sweeping movement standards, they left much to be desired to take out lumps.It is finished off with from the point of view of navigation.In glasspaper.It is advisable to place the two proportion to their length they were very Fig. 2.-Template for the hull parts together to make sure that they broad in the beam, and the poop rose high balance. The lower hull piece, B, in Fig. 3 above thewaist.From themodellingB, glued on at each side. Cut out the keel inshows the completed part. aspect,however,theymakesplendid1/8 in. ply to the shape shown by the thick These are now glued to the keel as in subjects, for the whole hull was- brightlyline on the design. It can be fretted out andFig. 4. Two or three nails can be driven painted, and coloured shields were fixedthe edges cleaned up with glasspaper.Thethrough the keel into one hull piece, but around the sides, giving a rich and decora-hulls, B, follow, and in this case drawingswhen fixing the other hull the nails must tive affect. of both plan and elevation are needed.be driven in askew through the hull at the It is a good plan to make a crease along aends. The nails are punched in and the Solid Hull Principle sheetof tracingpaper and make theholesfilledin with plastic wood.The Fig. 1 shows a model designed on thesetracings at each side of this in their correctcramps shown are useful to make tight lines. It measures just over 12 in. in lengthrelative positions as shown in Fig. 2. Ajoints, but the nails are necessary to prevent over-all, and is made on the solid -hullsuitable wood to use is pine or Americanthe parts from moving under the pressure. principle with the various parts built upwhitewood.Prepare the blocks totheNote the blocks of wood to prevent the one over the other.Scale diagrams arefinished over-all size and mark in the curves.surface from being damaged.

Figs. 3 and 4.-(Left). The two hull pieces B, and the keel A. (Right) The hull pieces glued to the keel 106 NEWNES PRACTICAL MECHANICS December, 1939

Figs. 5 and 7.-(Above) How the upper decks are mounted on the keel. (Right), The hull ready for painting

Upper Decks ter deck block E is given a sort of slopingvessel.The exact position can be taken These consist of a series of blocks mountednotch as in Fig. 5 so that in its lower partfrom the side view in the design.After upon the hull. At the stern are the twoit follows the round shape of the hull.Atglasspapering, the beak floor G is added. quarter deck blocks, E and F, and, although This is of 1/8 in. ply and it lies on the fore- they follow the line of the hull for the castle and projecting stem of the keel piece. greater part, they project at the extreme stern to form the square end as shown in The Bulwarks Fig. 5.The length can be taken from the For these 1/16 in.ply with the grain diagram, but itis advisable to place the upright is used. Two are required, and they wood on the hull so that the exact shape are cut to the shape H. The holes for the at the sides can be marked, the projecting ports can be either drilled or sawak. At the end being continued along in an uneven bow a cut is made so that the lower part sweep. Prepare and fix the lower block E will bend around the hull whilst the top first.It can be a trifle full to allow for is secured to the beak. Fig. 6 shows one shaping afterwards. The block F above it of the pieces fixed and the other being bent projects more than that beneath and is round. At the stern they line up with the hollowed out as shown, though this part of sloping notch. Use glue and fine nails for the work is best done after fixing.The fixing, bending the wood gradually. Punch taper, however, must be planed first. in the nails and fill in the holes with plastic The two forecastle decks C and D follow, wood.At the rear the stern piece J is and these are dealt with similarly. When the fixed between them, and the sides of this glue has set, the joints can be levelled and Fig. 6.-Bending the bulwarks round thesides must be bevelled so that they form close the final shaping worked with joints with the bulwarks and deck. shave and file.There should be a slightthe top it lines up with the block F above The wales and upright pieces are also inward slope towards the top, this increasingit.The line of the notch is in line with thein 1/16 in. ply. The shape of the former as the stern is reached. Note that the quar-wales which run around the sides of theis given on the design. The exact shape is

Fig.8.-Scaledia- gramsofthecom- ponentpartsofthe ship December, 1939 NEWNES PRACTICAL. MECHANICS 107 not important, however, because the woodFore mast, 7 in. by 3/16 in.Main mast,the dead eye, twisted around itself, and will bend to an extent in its width. Fig. 710 in. by fin. Mizzen mast, 7 in. by 3/16 in.taken around the other nail where itis shows them in position.This illustrationBowsprit yard, 31 in. by 3/16 in. Foremasttwisted into a loop through which the fixing also shows the beak roof I and its supportsyard, 5 in. by 3/16 in.Main mast yard,nail is to be passed. X, Y, Z.The last named are fretted out6 in. by 3/16 in. Mizzen mast yard, 5 in. by To these lower dead eyes those above are and fixed with a touch of glue. It is a good3/16 in.All yards are fixed to the mastssecured with loops of fine twine which plan to allow the glue to become tackywith a clenched nail before the last namedpass through the holes.Before these are before fixing as the parts will then stayare glued in place. Holes should be drilledaddedthemainshroudsare fixed in position.The roof I is also glued.Itto prevent splitting. with twine passed around the masts. They has a hole drilled through it to allow the should be all the same length with their mast to emerge, and it is as well to drill the dead eyes secured to their free ends. The hole in the deck before .fixing. Channels twine joining the two rows of dead eyes to hold the shrouds are cut in 1j8 in. or should be tied in a slip knot so that all can 3/16 in. wood. Screws hold them in position. be pulled taut.The cross pieces of the Finally the hatchisglued to the main shrouds if added can be lengths of fine wire deck and the remaining mast holes drilled.Fig. 9.-How the shrouds are - - bent around the shrouds and held by Painting the Model attached to the SL pinching in tightly with pliers. channelsand KNOT Showcard colours are the best to use. Sails Two coats are advisable, the first being hull rubbed down with fine glasspaper. The -The sizes of these can be set out from the portion below the wales is white, and the squared diagrams on the design.Lamp bulwarks brown. A light brown can be shade vellum is excellent for the purpose. used forthe wales and channels, and The heraldic device can be painted in touches of red and black can be given to showcardcolours.Thesailsareeither give a realistic effect to the figure head. Fig. 9 shows how the shrouds are securedglued to the yards or stitched on. A length When dry the whole thing is given a coatto the channels.The lower row of deadof twine joining the free ends will enable of clear cellulose lacquer.The design of theeyes have a piece of thin wire passed aroundthem to retain their bellied shape.The shields should be cut out and stuck to thintheir grooves.It passes thence throughaddition of the remaining shrouds and the cardboard. They are painted with a varietyholes in the channels to small nails drivenflags completes the model. of bright colours and glued around the sides.into the hull. To make the wires of the The stand consists of either two shaped same length drive a nail into a board andpieces of in. or 3/8 in. oak joined by a Rigging pass over it one of the dead eyes.Drive in. dowel glued to the holes, or of a solid The following are the sizes of the mastsin another nail 7/8 in. from the first.Thestand as in Fig. 1.The notches at the top and yards.Bowsprit, 5 in. by 3/16 in.wire is then taken around the groove inshould make a fairly tight fit over the keel.

Details of the Copying WithoutaCamera cooing process An Ingenious Idea for Copying Articles from Books Without Damaging the Book Thispaperisnotusuallystocked bybe developed up fully in the usual manner, photographicdealers,buttheycouldand you will get -a foggy_ looking negative probably obtain a supply to order. Alterna-image.. This paper negative is then fixed, tively, any contrasty grade of ,bromidewashed and dried. paper will give reasonably good results if The next operation is to make a positix: the paper itself is not too thick. copy from the paper negative. This is done by placing another pieceof the same 7,! How to Commence bromideincontactwiththenegative Let us suppose that we require a facsimilefilm to film-and exposing in an ordinary copy of a page from a book.First lay aprintingframethroughthenegative. pieceof bromide paper-sensitivesideIn fact, you just make a bromide print in downward-on to the page to be copiedthe ordinary way. The exposure this time and hold it down with a fairly thick piecewill take a lot longer than before. owing to BROMIDE of glass. CLEAR The glass may be weighted bythe heavy veil of fog on the negative, some- (FILM DOWNWAROS) GLASS standing a weight at each corner if necessary,thing between 30 seconds and one minute so as to bring the bromide paper into closewill probably be about right for a first trial. contact with the printed page. Arrange the T first sight it would appear essentialwhole lot under an electric lamp, as shownThe Best Results to use a camera for copying suchin the illustration ; all this must, of course, When thisprinthasbeenproperly subjects as the page of a book bybe done in the dark room by red light only.exposed and developed in the ordinary photography, but by making use of theThen make the exposure by switching onway, a good clear copy of the original method described below, such work can betheelectriclamp,thusexposingthepage should result.The best results are done without camera or plates. This is calledbromide paper through the back. This,obtained from a good black image on smooth the "Player -type Process," after the name ofperhaps, sounds rather a silly thing to do,white paper; creamy -coloured rough paper its inventor; it is very useful for copyingfor obviously, the bromide paper will bewill not be so satisfactory, but in such cases articles from a book, thus avoiding the work"fogged" all over; but never mind that,-an improvement will be obtained if the first of writing out the copy, or else cutting out themake a trial exposure, and when you getexposure is made through a slightly fibbed article and spoiling the book. You may, forthe exposureright you willfindthatyellow glass screen, if such can be obtained, -instance, copy an interesting page from aalthough the paper isfogged, the partbut the colour must not be very deep, or no library book ; it does not matter if the papercorresponding to the white background isresults will be possible. is thick or thin, or whether it is printed onmuch denser than the lettering, which will Although the writer has not actually both sides.Illustrations can be reproducedhe easily visible by transmitted light. tried it, probably a similar result to that, as well and itis possible even to copy This depends upon several conditions,obtained by using the screen could be photographs, although the results are notsuch as nature of copy, speed of bromideachieved, by using an oil lamp for making likely to be as satisfactory as a properpaper, thickness of bromide paper, the typethe first exposure.This would necessitate camera copy in such a case. of lamp used and the distance of the lamp.considerableincreaseinexposure, but As we are not making use of dry platesAs some sort of guide, the exposure shouldwould probably giveimprovedresults. for this process we naturally require somebe about threeseconds,using "Kodak Do not be discouragedif yourfirst other light sensitive material, and for thisContrasty Nikko" bromide paper, on a goodattemptisnotsatisfactory, and make purpose bromide paper will be needed.copy from a magazine printed on good whiteseveral trial exposures on small pieces of The most suitable for this work is "Ilfordart paper, with a 40 -watt lamp at a distancepaper only before risking a full size sheet, Photo -Mechanical Paper," which has aof 30 ins. from the book. otherwise your failure may become rather very contrasty sensitive film on thin paper. After exposure the bromide paper shouldexpensive. 108 NEWNES PRACTICAL MECHANICS December, 1939 A Mysterious Substance Facts About the Discovery of Radium and Its Varied Applications

EVER since 1898, when Prof. and Mme.radioactive material-or to give the instru-has in time a certain destructive action on Curie, working in conjunction withment its proper name, a SPINTHARISCOPE.all healthy human tissue, this actionis M. G. Bemont inParis, announced A B is a tube which may be of tin, wood,many times more powerful on certain types the discovery of radium, the word has beencardboard or similar material with twoof growths or diseased tissue. It, therefore, familiar to all of us, but few, outside thelenses mounted suitably at C and D. Thisdestroys the disease long beforeitcan medical and scientific world, realize exactlyslides in an outer tube, E F, which is closedaffect the healthy tissue and, with modern what this mysterious substance is. at the bottom by a disc G. The inner surfacemethods,theactionislimitedtothe of G is coated with ZINC SULPHIDE, whilediseased part entirely.The most usual What is Radium ? - a piece of wire, H, projects from themethod is to place tubular containers or In the first place, although radium istube E F in such a way that it is close to," needles" of radium or its emanation in classified as an element, in the strictestbut not touching, G.If a tiny piece ofthe growth itself, and these needles are sense of the word itis no such thing, forradioactive material (such as a scrap ofwithdrawn again after each treatment. it is actually a stepping -stone in a series ofthe coating off a luminous watch hand) is The use of radium in this field is a highly ever-changing phases whichcharacteriseaffixed to the end of the wire H, thespecialised job, and calls for a skill only Nature's surprising alchemy. Actually, weparticlesthrownoff bombardthezincobtainable from practitioners who have must begin with radium's ancestor uranium made a special study of radium -therapy, as which, through time and the workings of CRUDE. ORES -(PITCHEILENCE OR CARNOTJTE.) the operator must needs be, not only a LRCM -6 TO zooTONS nQUIREO Nature, gradually passes through various (fileRNIun OFViDiuM doctor, but a physicist as well. Were forms until it appears as radium-in other TOPRODUC.7I radium available to the general public, words radiumisan exceedingly active as say, Epsom -saltis. the damage done period in the transmutation of uranium to /OVUM would be incredible. the final stage in which it becomes that common elementlead.The process of 5LP14.4 PARTiCLES The Menace of Radium disintegration-one might almost say decay BET4 We have spoken of the danger of radium tle RAD/1J V -is the reason for the powerful emanations GRAMME --N\ GivItla .74w5 ICI in inexpert hands, and thisis indeed a or " rays " which are given out by radium, tu menace. Careless handling of radium or its RADON , RADON RAYS il and this process goes on at a fixed and Q1 salts by quite healthy people would result immovablerate. Theradioactivityis in sores being inflicted which are much unceasing, yet it takes over 2,000 years for POLONIUM Fig.1.-Radium with its asso- akin to the dreadedX-ray Burn " or half a given amount of radium to become ciated elements dermatitis, which martyred so many of the lead.Experiments have been made to heroic pioneers of Rontgen's discovery. process, and so unleash LEAD It may be easily understood that this theterrificatomic power containedin cesmks danger exists, but what is not so easy to radium, but to no avail, though such power, understand isthat there are" quack " if it could be tapped, would revolutionisesulphidecoating,causing brightscintil-medicines," cure-alls and " patent" nos- the whole world. Some idea of the powerlations of light on impact, which may betrums actually on the market, which are available may be formed when it is realisedclearly seen on viewing through the aperturesold under fancy names implying that all that there is sufficient potential energy inJ in a dark room. The cheap schoolboy'sthe wonderful benefits of radium may be ONE GRAIN ofpureradiumtoliftmicroscopes sold in shops are quite suitable,derived from their use. 5,000,000 tons weight one footoff theor the projection tubes of a toy magic These fall into two distinct categories. ground ! lantern may be easily adapted to make oneFirst the plain fake which is radioactive in Interesting as such speculations are, andof these fascinating instruments. name only, and does not contain any fascinating as may be the transition of the derivative of radium whatsoever. elements from uranium through ionium,The Benefits of Radium Secondly comes the smaller but very radium, radon and polonium to lead, it is Quite soon after the discovery of radium,important class which embraces " radio- with the by-products of this transition thatexperimenters found that, like the X-ray,active "waters,ointments,salvesand we are really concerned, foritis theseit could be used with distinctly beneficial" jars "-this latter type is a semi -porous emanationsthat make radium such aresults in the treatment of certain types ofearthen container in the wall of which are powerful factor in medicine and the treat-cancer. Thedevelopmentofradium -certain radioactive substances, and water ment of thatdreadfulscourgecancer.therapy has .progressed to such an extentleft in it for a specified period is alleged to Briefly there are four emanations, alpha become radioactive itself. particles, beta particles, gamma rays and A -,// 1:0/ri/M)7/10A1 radon-a gaseous emanation which isin A Danger itself radioactive. Certain preparations of the above type The alpha particles are actually doubly - actually do contain material more or less charged atoms of helium, and are thrown radioactive, and they are a positive danger off by radium at the amazing velocity of to health. Eminent specialists are agreed 10,000 miles per second. Astounding as this that, owing to the " cumulative " effect of speed is,itis a bad second to the beta B F. radium preparations, any such nostrum particles which are radiated at a speed Fig. 2.-Scction of a simple spinthariscope takenintothesystem anddispersed varying from 50,000 to 186,000 miles per throughout the human body may not only second, or at roughly the speed of light.that thousands of lives have been savedcause serious injury but actually death, for The gamma'ray (which is a ray in the trueand countless agonies alleviated by theradium attacks the bone structure and sets sense of the word) is identical with thatjudiciousapplicationofthiswonderfulup that terrible disease of the bones known produced by the X-rays. Radon, as before" element." as necrosis. mentioned, is a gas and, in medicine, is The natural result is that many people Furthermore, thereisno antidote or collected and stored for use just as anyhave jumped to the conclusion that radiumcurative treatment known to science for other gas may be. is a certain and infallible cure for all kindsthis condition, once the radium salts have of cancer, and that the only obstacle is itsdeposited in the bone tissue ! Making a Spinthariscope prohibitive price !Nothing could be more Much has yet to be learnt by science " Probably very interesting," you say, misleading. Radiumhasadistinctlyabout radioactivity, but in the meanwhile " but I'd like to see these emanations atcurative power over certain types of thethe " man in the street " may reap all its work." disease,butisdefinitelywithout anyknown benefits by seekingtheexpert That is a relatively simple matter, andbeneficial effect whatever in others and maywithout fear or hesitation, but to play with a glance at Fig. 2 will show you how toindeed, if used inexpertly, do more harmsuch a terrific source of power or to risk make a simpleviewer " for observing thethan good. Briefly summarised, the reasonits use without such expert guidance and bombardment of particles from any weaklyfor this curative action is that while radiumsupervision is a grave risk. December, 1939 NEWNES PRACTICAL MECHANICS 109

CELLULOID OBSERVATION -\ PANEL IN CENTRE SECTION WIRE -BRACED FIXED TAIL \. SINGLE WATER - COOLED, SURFACES WITH UN- SYNCHRONISED VICKERS BALANCED RUDDER & CALIN ELEVATOR COCKPIT EQUIPPED WITH. THE SIMPLEST OF INSTRUMENTS: A.S.I., REV. COUNTER.. ALTIMETER L SO ON

23 - PETROL Or - ,TANK

RUBBER CORD SPRUNG STEERABLE TAIL SKID

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SRRUNG. WHEELS / SPRUCE INTERPLANE STRUTS WITH STREAM- LINE WIRE BRACING FABRIC -COVERED WIRE CYCLE -TYPE WHEELS FABRIC -COVERED WOODEN WITH THIN HIGH-PRESSURE MAIN PLANES WITH SPRUCE TYRE SPARSt,-. LATTICE RIBS The Pup, a fighting plane of the Great War Flying in the 1st Great War By G. Long, F.R.G.S. THERE is no more wonderful story Infact 4 am doubtful if any service obtained than that of the Air Force in the THE PUP, 1916 such splendid keen young men as the GreatWar. Fewpeopleto -day Maximum power 84 b.h.p. pilots of the R.F.C. Many came from the 26 ft. 6 ins. realise how crude, inefficient and dangerous Length ... 19 ft. 4 ins. Public Schools, but all were intelligent, were the machines on which those intrepid Wing area 254 sq. ft. plucky, and enthusiastic. pioneer pilots risked their lives.Engines Weight empty 787 lb. In the course of the war our airmen Weight loaded 1,225 lb. at first were air-cooled-like clumsy motor- Speed at 6,500 ft. 106.5 m.p.h. destroyed more than eight thousand enemy cycle engines-and grossly underpowered. Speed at 10.000 ft. 104.5 m.p.h. machines, dropped more than eight thou- usually 70 or 80 h.p. Valves would break, Climb to 6,500 ft. 8 minutes sand tons of bombs on enemy objectives, Climb to 15,000 ft. 30 minutes bearingsrun,or the whole contraption Ceiling 20,000 ft. broughtdownthreehundredenemy seize up at the slightest provocation, and Endurance 3 hours balloons, and took over half a million when such a disaster happened near the photographs. In August, 1914, there were ground a fatal crash was highly probable. THE HURRICANE,1939 fewer than two hundred and fifty officers, Maximum power 1.030 h.p. The 'planes too were no better, ricketty Span ... 40 ft. 0 ins. in the whole service, in November, 1918, " crates " at best, dangerous death-traps Length ... 31 ft. 5 ins. there were more than thirty thousand, and at worst, they were built of woDd and Wing area ... 257.5 sq. ft. the thirty-seven 'planes which crossed the Weight empty 4,670 lb. canvas, and held together by wires like Weight loaded 6,000 lb. Channel at the outbreak of war had grown a bird cage.Often they broke up in the Speed at 17,500 ft. ... 335 m.p.h. to twenty-two thousand, and formed the air when meeting sudden gusts of wind, or Normal cruising speed, 15,000 ft. 276 m.p.h. greatest air force in the world. Stalling speed ... 68 m.p.h. stalled and crashed when taking off.The Service ceiling ... 34,000 ft. The High Command of the period were fact is,of course, that flying was inits Endurance, at 200 m.p.h. 800 miles not air -minded. Only a short time before infancy when the war broke out in 1914. the war began our War Office twice refused On November 1st,1910, there were only the offer of the first really successful 'plane. 22 pilots in all England and the first crossingdiscovering that three German Army CorpsThe generals had never flown themselves, of the English Channel (in a 25 h.p. mono-were attacking Le Cateau instead of one,they had no experience of air warfare, and plane) had only taken place one year earlier.as imagined by the British staff. their text books were silent on the subject. The first flight over English soil was made SirHoraceSmith-DorrienwroteonIt was the young men of the flying services by Mr. A. V. Roe in 1908 with an AntoinetteSeptember 9th, 1914 : who built up our matchless air force. They Engine, and a year later he flew with an all Our aeroplaneofficers are realheroes.workedoutproblemsofstrategy and British J.A.P. engine of 9 h.p., but it wasNot only do they appear to have put thetacticswhile soaring through the _skies not until 1912 that the Royal Flying Corpsfear of God into the German airmen, forin their primitive " crates " and not in the was founded, and the Army officially tookthey hunt them wherever theyseethem,padded armchairs of G.H.Q. up aviation, but progress was so slow thatwith the result that there have been none when war broke out in August, 1914, onlyin the air for two days, but in spite of beingFighting 'Planes 37 machines were fit to go to the front.shot at every time they go up, they continue They soon exploded the uninstructed They all flew across the Straits of Dovertheir reconnaissances, and bring back quitetheories of mere foot soldiers. The first of and arrived safely at Amiens on Augustinvaluable information." these was that a 'plane was a mere scout, 14th. The 'planes were mostly B.E.'s and and incapable of fighting.Within a few B.E. 2C's, with a few monoplanes. They wentThe R.F.C. weeks,ourairmenwerefightingthe into action at once and during the Retreat Having served with them in the R.F.C.Germans with pistols or carbines-usually from Mons they staved off a disaster byand the R.A.F. I know that this is true,without effect.The first German 'plane 110 NEWNES PRACTICAL MECHANICS December, 1939 was forced down by an R.F.C. scout usingwaiting to swoop down on the unsuspect-the heart of the empire was to become a a rifle on August 27th, 1914. The Hun wasing foe. flaming ruin.One Brass Hat even said in a " pusher " 'plane (that is one with the Formation flying was another develop-that the proper remedy for Zepp. raids propellerbehind).The Englishmangotment, it was modelled on the phalanx ofwas darkness and composure on the behind-sat on his tail-and couldnotantiquity, and its basis was the triangle.part of the civilian population. In view of befiredat by reason of the German'sThe leader flew in front. and had two otherthe fact that raiding Zepps. actually lighted propeller. machines slightly behind and above. Theup their objectives by dropping parachute Atfirst" pushers "werefavoured, rear machines by diving can overtake theflares,and sailed away unscathed,the because they gave a free zone of fire forleader and support him.Sometimes oneabsurdity, of this remark isself evident. shootingahead,but" tractor "'planessuchtriangleissupported by anotherHappily, however, the skill °Pour inventors, were more efficient because the propellertriangle overhead and somewhat totheand the courage of our flying men solved in front got a better grip of the air than arear. The British airmen were the first tothe problem. The first Zepp. was brought screw behind, where the air was broken upprove the fact that if you charge an enemydown in Belgium by Sub.-Lieut.R.J. by wings and struts. plane directly, hewill sheer off-but itWarneford, afterwards awared theV.C. Thenextcleverinventionwasthetook some pluck te,do it.The 'planes ofHe dropped six bombs upon it, and the machine gun firing through the propeller.that period werecontrolled by asingleexplosion turned his 'plane completely over. The number of revolutions of theprop "lever-called the ' Joy -stick." If you pushThe debris of the Zepp, fell on a convent were anything from 1,200 to 1,400 perit forward the nose of the machine goesand killed two nuns. minute, which means that there would bedown,ftyot,pul i back the machine blades in the way of the gun twice thatbegins to climb. banking was also controlledSpectacular Exploit number of times in a minute. The machineby it in a similar fashion. More spectacular, because witnessed by guns of the period fired 500 to 600 rounds millions of Londoners was the exploit of aminute, and thefirstideawas theWar On Zepps. Lieut. Robinson on September 3rd, 1916. " deflector " prop which was a propeller No story of the R.E.C. in the Great WarThirteen Zepps. raided England that night, armoured with steel plates at the pointwould be complete without telling how ourset three gasometers on fire at Retford and where it might be struck by a bullet. Bygallantairmen smashedtheZeppelins.did extensive damage elsewhere.Five of this arrangement all but about 5 per cent.These great ghs-bags could fly very high,them reached London, one of them-a of the bullets paSsed through the propellerand for a long time they bombed LondonSchutte-Lanz semi -rigid type --was flying without striking it, but the bullets seriouslyand other cities with impunity. Althoughat a height of two miles when the heroic affected the smooth running of the engine.the Air Peril ought to have been realized,Robinson sightedit. Ignoringthefire and in a few cases actually broke the propand preparedfor,fromthe veryfirst,from its machine-guns, and the shells of our with disastrous results. nothing whatever was done by the WarA.A. guns, he fired a stream of tracer bullets There came next a really brilliant idea. Office.London's first anti-Zepp. defenceinto the envelope and only barely escaped It was an interrupter gear, which preventedconsisted of a machine-gun mounted on adestruction in the flaming ruin, as it crashed t he firing of the gun during the brief periodsmotor car: It was in any case hopelesslytotheground. MillionsofLondoners of time that the blades were in front of theoutranged, but if it had struck the gas -hagsawthissplendidexploit, andcrowds uzzle. it would have had no effect.It was muchflocked to view the ruins of the " Zepp " All this time tactics were being workedlater that a clever inventor produced theat Cuffley. out.The great thing was not to let anluminous'' tracer " bullet, which enabled From that date the Zeppelin peril was enemy get on your tail " in which casean airman to direct a stream of bullets on aovercome. Many more were brought down he might shoot you down before you knewtarget like a gardener -working a hose. Hein flames, and on October 19th, 1917, they lie was there. If your gun jams so that youcould see when his aim was correct, and themet their Waterloo. Twelve of the largest cannot fight, the idea is to fly at rightfire -bullets quickly put paid to gas bagand finest Zepps. set out on a " baby - angles to the enemy, as it is very difficultairships. killing " raid over England, but only four o hit a machine so crossing. Nothing was more disheartening to thereturned to Hunland. In order to escape British public that the complete impunityour 'planes they were forced to fly at a A Favourite Dodge with which the early Zepps. bombed ourgreat height, where their engines froze up. A favourite dodge was to hide in a rcloudgreat cities. The High Command appearedThe Zepps. were then carried by the wind bank, and pounce on an enemy below.totally indifferent, and it seemed impossibleover France to the Mediterranean.Five Sometimes big slow bombers weresentto make them see that it was of little availare known to have been brought down in asa baittoattractenemyfighters,to capture fifty square yards of water-France, two were driven out to sea, and whileour own fightershighaloftwere logged shell holes in Flanders, if meanwhiletwo were lost altogether.

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The "Hawker- Hurricane, which is oneofthe fighter planes now in use December, 1939 NEWNES PRACTICAL MECHANICS Synchronising Sound with Your Cine How Gramophone Records Can be Made for Use in Conjunction with Cinematograph Films

There are several points to watch whenbeing ready tracked and requiring only a making records, and it is not proposed torecording head or pick-up.The recording THE hometinemayfrequentlydeal with them here, since space does notpick-up can be connected as shown in Fig. 1. beusedtoprovideconsiderablypermit.Most of the suppliers of recordwhere it takes the place of the loudspeaker better entertainment if it can be con- in a choke -capacity output circuit of the verted to a form of " talkie." Of course, it broadcast receiver,. which is to be used is now possible to obtain a complete " home as an amplifier. When choke -capacity out- talkie " outfit, but the price is very high. put is not used, the speaker being connected Even when cost does not prohibit its use, directly between the anode of the output itis seldom that suitable sound -picture valve and H.T.-the pick-up can be con- renes can be " shot."As an alternative, nected as shown in Fig. 1, but using the the tine enthusiast might consider the speaker in place of the choke. In that case possibilities of making gramophone records it will be desirable to disconnect one of the to syhchronise with the reproduced pictures. secondary terminals on the transformer Briefly, the idea is that the film should be from the speech coil, but this is not essential thrown on to the screen at the same time when the set provides upwards of 2 watts as a gramophone record is being made.If output. Incidentally, an output of at least both film and record are started together, watt is needed for good results. they can later be reproduced at the same A microphone should be connected to the time to give the same effect as a sound film. pick-up terminals of the receiver or ampli- fier.Then, with the film running and the Question of Cost pick-up on the record, it is necessary only The method of procedure can be either to speak, play, sing, etc., into the micro- dimple or fairly c3mplex, cheap or rather phone, making the sounds coincide with the costly, according to the amount which can pictorial events. be spent and the quality of reproduction demanded.When itis not proposed to Preliminary Experiments spend more than a few shillings an ordinary It might be necessary to make a few gramophone pick-up can be used as a Fig. 1.-Connections suitable for a pick-up used as experiments before the desired results are recording head in conjunction with a loud - a recording head. A mains set is assumed, but the obtained, for which reason it is suggested tone needle ;it might be found necessary method is the same for a batteryreceiver that the record be stopped every half - to weight the pick-up head in order to ensure minute or so and " played back." This will a better " cut " in the record blank.Asblanks, however, will provide the necessaryenable the operator to judge the best to the latter, it might be possible to obtaininstructions for their efficient use. positions for the microphone volume control for certain kinds of sound, and will neces- a few aluminium blanks very cheaply,Recording although it appears that there are not now sitate the waste of only a single record many of these on the market.There are In the first place, it will be assumed thatblank. Before commencing the " full dress " many other types, however, although manyaluminium blanks are being used, theseperformance it will be helpful to run through of them cannot be usedsatisfactorily, exceptinconjunction with a complete recording and tracking head-which costs something like four guineas on the average. One well-known type of record blank is the " Musikon " ; this requires a proper record- CT 040M ing head and has to be " processed " after recording.The " processing " consists of / Mco. bakingthecomparativelysoftoriginal record. The baking makes it quite hard and 'may reasonably permanent. Another Record Blank There is another type of record blank - available which does not require to be y IT* baked.This is similar in appearance to "1"-x- 1177- the normal type of record and must be used Li - in conjunction with a tracking head. After 8# recording, a small amount of special chemi- cal is applied to the surface with a wad of cotton wool, and then the surface is polished by applying a second solution in a similar manner. This simple treatment renders the record perfectly hard and suitable for use time after time. Yet another pattern is of semi -transparent material, rather like cellu- loid in appearance.With this record no processing is necessary, but itis not as permanent as the others. Fig. 2.-A useful type of double -push-pull circuit for recording 112 NEWNES PRACTICAL MECHANICS December, 1939 the film three or four times. making notes _adconnection onlyofthesecondary. of the best sound accompaniment and of the number of words which can be spoken A Simple Amplifier inconnection withthevariousscenes. Another method is to use a double -push- Those who are able to write shorthand will pull amplifier, of the general form shown in probably write out the script, correcting Fig. 2.This is for a battery -fed amplifier and " cutting "iteach time the filmis using two triodes and two high -efficiency shown through as a preliminary to record- pentode waives. Those who propose to ing. build an amplifier especially for recording or low -power public-address use will find Input Connections that one based on this general circuit is very In many cases it will be found better to satisfactory.Of course, the output, when record both speech and music,fading in using battery valves, will not be more than either as required. Gramophone records will I watt for an H.T. current consumption of be- useful for the musical portions, and so about 20 mA.But by using a mains - both a pick-up and microphone will be operated amplifier a much greater output required. These may be connected as shown could be obtained. It would not be possible in Fig. 3.In this 'case there are two triode - to give full constructional details here. but input valves (H.L. type are suitable), the the brief particulars supplied by the circuit output from these being fed into a commo: diagram will be sufficient for the guidance output valve, or into a pre -output amplifier. of experienced constructors. Two separate volume controls are used, and Fig. 3.-Method of using two input valves for the After the records have been made they these might be either on the microphone pick-up and microphone.Both feed into a single can be played through in exactly the same andpick-uprespectively,ormounted amplifier valve mannerascommercially -maderecords. separately near the amplifier.The latter using a pick-up, amplifier and speaker.If arrangement is better, since they are thencoupling, but transformercouplingcan they are labelled to agree with the title of moreaccesaleandcanbeoperatedbe employed by using a push-pull trans-the film to which they are appropriate, a simultaneously withoutdifficulty. Theformer with centre -tapped primary, andcomplete album of sound-eine combinations connections given are for resistance -ca parityby employing the centre -tapping and onecan be built up.

THIS' MONTH IN THE WORLD OF Soap Fruit EFORE soapwasinventedplants SCIENCE AND INVENTION Bwere used for washing. To -day there is a tree in tropical America which has a soft pulpy fruit having many times the Mon Becoming Taller 1,000 Years Hence emulsifying andcleansingpropertiesof worth of manicure sets, per-manufactured soap-and it will not shrink RECORDS taken over the pastthirty woollens. years show that schoolgirls of eleven LIt 00fumes and powder puffs are are to -day two inches taller than girls ofto be buriedinthemountainsnear the same age only ten years ago. In severalTucson, Arizona. A granite pillar hearingThe Speed of Birds in European countries the height of conscriptsthe inscription "Do not open until 2939 is joining the colours shows a similar increase,to be placed over them. Flight amounting on the average, to about one SCIENTISTS have often tried to solve the inch, in the period of the past 25 years. TheNew Synthetic Fibre problem of how small birds are able to increase is sometimes put down to improved FROM Tokio comes the news that afly for hour after hour over oceans and diet, and this view is supported by the fact Korean research doctor has discovered adesolate country.This problem has now that, in America, a colony of rats fed on thenew synthetic fibre made from lime, coalbeen partly solved by pilots on the Pan- best possible diet over a period of twenty-and acetylene gas. The feature of the fibreAmerican Airways routes who were asked five years has shown a steady and con-is that it is as elastic as wool and four timesto make notes of the speed and the height tinuous advanceinsizethrough manyas strong. It can be easily dyed, and weav-of the birds they saw. The theory that birds generations. ing machines for handling viscose rayonfly at fairly slow speeds near the ground can use this new fibre.It has been calledwhen migrating has been disproved by the Synthesis No. 1. notes.It was found that they fly in the Dead Reckoning PP clouds at a height of about 31 miles from GREENWICH TIME is considered to be"As Quick as Lightning the ground, and in this way they are able absolutely accurate but astronomers THE above expression, which isoftento cover great distances in a short space of are sometimes worried because the clock is used, has lost some of its effectivenesstime. Constant winds blow at this height occasionally a tenth of a second wrong. now that scientists have found that its rateat up to 100 miles an hour, always at the They are therefore building a clock whichof travel is only 10,000 miles a second assame speed and in the same direction. The will not vary more than a hundredth of acompared with light with a speed of 186,000birds are thus aided by the winds and with second. The revolving earth, which is nevermiles a second.Whilst on the subject oflittle effort sail along at the same speed as fast or slow, is the standard clock and bylightning there is a belief thatitneverthe wind. observing the stars astronomers can tellstrikes twice in the same place.This is the time with complete accuracy.Theincorrect, because it does-and sometimes as BOOK RECEIVED drawback with this method of telling themany as four or five times. time, however, is that heavy clouds often " The Beginner's Guide to the Lathe."By obscure the stars for considerable periods, Percival Marshall.Published by Percival so an accurate clock is necessary to fill in THE HOME MECHANIC Marshall & Co., Ltd.88 pages.Price the gaps from one time -observation to the Is. 6d. net. next. The electric clocks in present use are THIS is a useful handbook for amateurs controlledbypendulums,butforno ENCYCLOWED IA desirous of making their acquaintance with the lathe and its uses. The first part of apparent reason all pendulum clocks have An up-to-date and comprehensive guide to a tendency to start running a little fast or the Mechanical, Scientific and Technical the hook describes in simple language the

slow. The new clock is similar t4 a mains Interests of the day-with expert articles various parts of plain lathes, self-acting and on Aircraft, Television, Models, Astronomy. screw -cutting lathes.Methods of holding clock which regulates itself by pulses of Electricity, Photography, Chemistry. Wood- current from a dynamo, but differs in that work, Motor Cars, Wireless, Home Cinema, and driving work, turning in wood and it makes its own alternating current and with over 600 illustrations. metal are next dealt with, followed by a times itperfectly by means of a piece of Only 3% Net description of the slide -rest and its uses, and rock crystal which vibrates 100,000 times a drilling and boring in the lathe. The book, second. The clock will be kept at a constant 4%. post free from the publishers, Book Dept., George which is well illustrated, contains all the Neuwes,Ltd.,Tower House, SouthamptonStreet, temperature all the year round, and would Strand, London, W.C.2 information necessary to enable the begin- run for a year without losing or gaining a NEWNES : LONDON ner to make a start in the fascinating craft third of a second. of turning in wood or metal. December, 1939 NEWNES PRACTICAL MECHANICS 113 BUILDING A GLIDER

43. Lightinweight and a staple Flyer, this gliderfully SPRUCE BAMBOOTIP TAPERING conforms withallF.A.I.Rulings andiseligiblefor TO 3,16x43. 118x3/4 SHAPED IfSQ LE BALSA the King PeterII Cup SHAPED I.E. FUSELAGE HEIGHT 10" WIDTH F BASE 10. 2 y2 2Y2 NOSE BASE BLOCK It'SHEET BALSA - 0" - MAX.,'I9R6Y" 3 _t 46 27444 2.P2' BAMBOO PLANK WITH ArSTRIP BALSA kiXCPLYWOOD WITH HOOKS FOR WEIGHT 34ozs Constructional LAUNCHING WIDTH OF FUSELAGE -2e OF DEPTH details of the OVERALL LENGTH -5 FT fuselage THIS gliderfully conforms with allmounting for the tailplane can either befully bent to shape and firmly cemented in F.A.I. rulings, and can be flown inbuilt up, or carved from a very soft blockposition. Care should be taken when bend- any contest under their rules.It isof balsa which is cemented into the rearing the bamboo to see that it is not cracked also eligible for the King Peter II Cupend of the fuselage. The noseblock is carvedor scorched. contest for gliders. from a block of hardwood and hollowed out Cut the required number of tailplane ribs, Built mainly of silk and spruce, it is veryto receive the weight required for balancingfrom*in.sheetbalsa(the maximum strong, and is also a very stable flyer. the model.This will be approximately 6section is shown full size) and shape the Draw the plans carefully to full size. Theozs. Once the model is correctly balanced,leading edge from fin. square balsa.Care- fuselage is built slab sided first of all, thenthe noseblock can be cemented to thefully cement the two spars of fin. x fin. *in. sheet balsa half circles are added tofuselage. spruce in position and then shape the trail- the top and bottom, in order to streamlineThe Rudders ing edge of fin. x Sin. balsa. Bend two tips it. The method is shown in the drawing of The upper and lower rudders are thenfrom a piece of bamboo and cement them the maximum former. built on to the fuselage. The section of thefirmly in position. Cover the top and bottom The main structure is f -in. square spruceupper rudder is biconvex, slightly thinnerof the tailplane each side of the centre rib and when the half circles are added, a fin.than that of the tailplane (which is drawnwith din. sheet balsa, as shown. square spruce stringer is here). bottomandten*-in.squarespruce The leading edge is shaped fromThe Wings stringers are added, in each half circle asfin. square balsa, the trailing edge is shaped Cut dip required number of ribs from *in. shown. The tail- The Keel plane sec- MAX TAILPLANESECTION The plywood keel in which 3 hooks aretion which SHAPED FROM SHAPED FROM shaped, is cemented in the formers, in place measures8 kesQ.BALsA VEN343ALSA of the f -in. square spruce stringer, betweenin. in chord 'xIssnucs '

BOTTOM COVER 213TOP WITH I43 ALSA sheet balsa and shape the leading edge from BAMBOO TRAILING EDGE '43x3/4.SHAPED BALSA TIP Sin. x fin. balsa and the trailing edge from lin. x fin. balsa. A plan view The wing is built in four pieces.Build TWO Y41

40'

-0- A Dion view of the wing 114 NEWNES PRACTICAL MECHANICS December, 1939

Great care must be exercised in building vSO.SPRUCE coats of clear dope, and then the model the wing, and especially when making and can be finished with coloured dopes to suit WING MOUNT ON reinforcing the joints.Firmly cement 4FORMERS Nos5,6 the modeller's taste. long bamboo pegs into the leading and7,8 Assembling the Model trailing edges where shown. The whole The model should be assembled by fitting machine can now be covered with silk. 2" the wing on the wing mounting, in the This should be applied damp as it will position shown, and passing several rubber tighten when dry.The best adhesive is bands, at least Ichi. wide round the fuselage Gripfix, as this allows the silk to be pulled from the pegs cemented in the wing. These tightly over the framework and if misplaced bands should be strong enough to hold the it can easily be lifted up and replaced YIFi SHEET BALSA wing firmly in position, but see that they correctly. are not too tight, as they are likely to Covering the Fuselage Vg SO.SPRUCE 2'damage the fuselage in the event of a heavy The coveringof thefuselageshould landing.The tailplane should fit tightly present little difficulty, except around the between the shaped rudder base, and the wing mount, where care has to be exercised hd SHEET BALSA shaped block in the fuselage.The wing to see that the silk is tight and unwrinkled. should be set at 24° pos. incidence as shown Then' cover the upper and lower rudders on the drawing, and the tailplane at 0° with silk, but be careful that the silk does incidence. The weight in the noseblock can not warp the lower rudder when drying. now be adjusted until the model balances at ALL SMALL 2' Cover the tailplane carefully with silk, andSTRINGERS4:7 the points A and B (marked on the wing be sure that.it lies smoothly over thehin.Vie SO. SPRUCE drawing). balsa sheet covering in the middle. Only very slight adjustments should then Lastly, comes the covering of the wing. be required for perfect flying trim.The First, cover the undersurface, and here a 1/8.50.SPRUCE model should normally be launched off the ulue such as Seccotine will have to be used. middle hook and on fairly calm days off Carefully smooth out all the wrinkles and(Above) Size and shape of maximum former. (Left) A the back hook. The front hook should he section of the wing which is 10 in. long. (Right) A front used on very windy days. WING SECTION view of the glider The total weight of the model, when com- pleted is 34 oz., and this should be borne in

SHAPED FROM 3/4" X 3/44 x 348"SPRUCE BALSA 4 ygSQSPRUCE

SHAPp FROM I X tit BALSA then cover the top of the wing.Care willbut with a little patience these can bemind by the reader, if he thinks that some have to be exercised in the covering at thesmoothed away. of the reinforcing is not necessary, or that tips, asthesilktends to wrinkle here, When the silk is dry, apply two or threebalsa could be used instead of spruce.

of fur coats, the hair -face being on the out- side of the cloak, which is provided with NEW INVENTIONS a fabric lining. A Nose Filter and aUse for Horse Hides With this invention, horse -hides may be utilised in the manufacture of garments high cost of petrol, the, faithful animalsuch as coats, cloaks, sports jackets, etc. Nose Filter which, for many centuries, has carried andAccording to the new process, the hides are IN the days of Queen Victoria 'delicate folkdrawn man and his wares, has returned tochamois -dressed to show the nature of were seen wearing what was termed aour streets. chamois -leather or deerskin at the leather respirator. In those alleged good old times Now the hide of the horse will come intoface.The garments are made in such a mustard and other harmful gases were notthe limelight (the black -out permitting) ifmanner that the leather face, prepared as known in warfare.The enemy againsta recent inventionissuccessfully com-mentioned above, is at the outside. On the which the respirator in question was pro-mercialised.I learn that, hitherto, horseinside is the hair -face which warms the wearer vided was cold air. To protect against thishides have been used only in the manufac-and makes a separate lining unnecessary. foe, the mouth was shielded with a kind ofture of leather for soles.And the skins of The leather face may be coloured in any sieve or filter, which was attached to thefoals have been employed in the productiondesired shade. "DYNAMO." face by means of loops over the ears. Like the current gas mask, this respirator was certainly not an ornament to the counten- ance. AN IMPORTANT ANNOUNCEMENT Qf an imperceptible character, is a nasal WORKING MODEL OF THE FLYING SCOTSMAN filterwhich hasjust made itsdebut. We have received during the past two years a large number of requests from readers for working drawings of a model of the Flying Scot.Accordingly, we have pleasure in announcing that the first of a series of articles describing the con- Inserted in the nostrils, this filter is intended struction of a working scale model in 24 inch gauge of the Flying Scotsman, will appear in next month's issue. Every to prevent pollen, dust and injurious germs detail will be shown and full instructions will be given for building a realistic replica of this famous locomotive. We from entering the nasal passages. Nature have had the machine built in the workshops of Messrs. W. J. Bassett-Lowke, Ltd., and stage by stage photographs and has already designed the nostrils with the drawings will illustrate the text. object of barring the entrance of hostile Next month-first of a series describing the 24 inch Gauge Flying Scotsman. particles. If we were to cultivate the habit of breathing through the nose, it would be very greatly to our benefit.Apparently yet further to protect the human subject, this filter has been contrived.It is fitted with a fine mesh impregnated with a com- pound, the vapours of which are said to shrink the mucous membrane. As a result, the inhalingof harmful germs,ifnot entirely prevented, will be reduced to a minimum. New Use for Horsehide AHORSE ! A horse !My kingdom for fl a horse ! " cried King Richard III. Well, the horse is coming into his king- The L.N.E.R. 2inch gauge " Flying Scotsman " which willformthe s ubject of a new series of dom again.Owing to the rationing and constructional articles starting next month December, 1939 NEWNESPRACTICAL MECHANICS I 15 1#1042741' SC NT1STS N HOSTS The Unsolved Problem of Ghosts and Their Hauntings no doubt, we all think them absurd anduntrue, for most accredited accounts of senseless enough, as most of them, perhaps,spectralmanifestationshavesomany undoubtedly are. Behind all g.lost stories,points in common that itis possible to other than those of acknoicledged fiction,generalise very definitely on this subject however, there is a basic residue of actuality,without bringing in individual instances for and few, indeed, are the thinking menspecial consideration., who would deny such a fact. CHRISTMAS is traditionallythe Three Alternatives period of ghosts and hauntings, theGhosts and Scientists There are only three possible ways of season of the year at which the The scientist, of course, does not like theexplaining a ghost or a ghostly manifesta- more venturesome of supposed discarnateghost, for the spectre, and its many weirdtion, although, of course, each of these ways spirits are alleged to thrust their inexplic-phenomena, consistently refuses to fit intocan be varied almost indefinitely. able presences upon us for the sake,itthe prescribed domain of science. And that In the first place, all cases of hauntings would seem, of disturbing certain individualsis why, perhaps, the professed scientistand apparitions can be put down to pure and exciting in them a due attitude ofhas as little to do with ghosts as he possiblyhallucination on the part of the individual. terror and dismay.. can. Not being able to explain them in anyThat is to say, such happenings have no Why, however, the peaceful season ofadequate terms, he almost automaticallycause or being outside of the consciousness Christmastide, with its atmosphere of good-inclines to ignore them. of the person who experiences them. will, has so frequently, in legend and in Still, however, the phenomena of haunt- This explanation is, naturally enough, to story, been associated with the appearancesings and of manifestations rise up continu-many persons, a very satisfactory one, for of eerie visitants from another sphere ofally here and there, even in the most crowdedit simply says that ghosts are all bunkum, existencehasneverbeenadequately explained. Maybe, as is more probably the case,themajorityoftheseChristmas ghosts have never been anything else other than mere figments proceeding from the imaginationsofcountlessstory -tellers. Certainly, all Christmas ghosts exhibit, if one believes the many stories concerning asso them, a great degree of sameness and of conventionality,so much so that such 'VI0 , c) . o spooks are now regarded by the British , Q00 public as part and parcel of the traditional CINEMATOGRAPH atmosphere of Christmas, in almost the ii11111111111i-7--, same manner as the holly, the filled stock- PROJECTOR ings, the Christmas log and the indispensable plum pudding. " All -the -Year -Round " Ghosts But what about these ghosts and their hauntings which have no connection with Christmas festivities, and which,if the related circumstances of their appearances are in any way true, represent the very antithisisofChristmascheer ? They present a far deeper problem to the thinking individual, if only for the reason that they cannot adequately be disposed of (like a Christmas ghost) with a smile and a wink. These " all -the -year-round " ghosts, indeed, DORMANT PERSON DISTANT PROJECTED are apparently real and substantial ones, IN CHAIR that is to say, if any type of apparition may "GHOST" OR REPLICA be sostyled,and,inmany instances Just as images can be projected on to a screen, one theory of ghosts asserts t4at, in certain conditions, the very nature of their hauntings, with its a "living" image, replica or counterpart may be projected by an individual to any distance character of constant repetition, seems to put out of court the charge of such pheno-of our cities. They are usually hushed up,and that they are utterly imaginary and mena being merely hallucinatory. for we all have an inevitable tendency tonothing else. Few thinking people take this No matter what the individual may say,keep quiet on matters which we prefer notview, however. Even scientists don't. there is no doubting the fact that mankindto think about. Hence it is seldom that The second explanation of ghostly hap- in the mass is a believer in ghosts. Righteven the most accredited ghostly manifesta-penings is, to put it rather strangely, that from the earliest beginnings of recordedtion is given a full ventilntion of its detailsthey do actually happen.This general history, through the folklore and the storiesin the light of day, so to speak. Occupy-explanation would have it that ghosts and of all nations, civilised and uncivilised alike,ing a house in which there is a ghost orall their various paraphernalia do actually one comes across, times without number,some unexplained manifestation is re -actedexist apart from our consciousness and that the story of the ghostly visitant, of theto in much the same manner as living in athese entities have a being of their own unexpectedandmystifyingoccurrencehouse in which there are mice or black -either in or out of Time and Space. which can only be explained (or, rather, tobeetles.The unwanted parasites are fre- General explanation number three states be more accurate, which, in the past, hasquently accepted, so long as they do notthat all ghostly phenomena is the result of only been explained) on the assumption ofinterfere too greatly with the normal modetelepathic activity on the part of living or its being caused by intelligences beyond theof living. dead individuals. On this theory a spectre reach of a living man. It is not the purpose of this article toor a ghost has no actual existence.It is We all have our pet ghost yarns, and,relate any particular ghost story, true ormerely an image projected by some other 116 NEWNES PRACTICAL MECHANICS December, 1939 person, living or dead, and it is no moreted hauntings nowadays are those of theAn " Energy " Pattern tangible as an existing entity than the" poltergeist,"or " noisy ghost "which If, in the above -mentioned instance, an image of a film star projected upon themanifests itself not in any visual apparitionsenergy pattern "isinsometotally screen of a cinema. but in sundry and oft -repeated mysteriousinexplicable manner formed in Time -Space Whether a dead person, or a disembodiedand uncanny noises, such as knockings,as the result of a violent death or from intelligence, if we so prefer to use the lattershufflings,wailings and soforth.If aother circumstances,itisquite feasible term, can possibly project a- living "house which is infested with such mani-that the resulting ghost and;or the various image of itself or of some other individualfestations is pulled down, the phenomenaphenomenal haunting may arise from the or thing, we have no possible means ofcease at once and do not recur. energy complex gradually dissipating itself telling., It does seem definitely possible, seems.jjerefore, that if you are ablein one recurring set of manifestations, just however, for a living individual to projectto destroy the close material associationsas the playing of a gramophone record is a distant ghostly image or replica of him-of the ghost you can destroy the ghostthe result of the energy of the instrument's self under certain abnormal conditions,itself. motor dissipating itself through the one and in this way is explained with a fair Another fact connected with hauntingsparticular sound pattern of the record. amount of feasibility the phenomena ofisthat, although they are repetitive in Regarded in the light of this " physical " " bilocation," or the ability to be in twonature, the intensity of the manifestationstheory, a ghost is nothing more than a places at the same time which has apparent-tends gradually to become weaker andpicture on a screen, even though it may ly characterised a few religious ascetics inweaker. move and perform all sorts of mysterious the past, and, also, the often -heard modern It almost seems as if all this ghostlyand complicated actions.Such a spectre accounts of an individual appearing tobusinesswithitsrecurrencesanditsis merely a visible yet quite impersonal another distant one at the moment of thesenselessharping on oneselected andmarionette which is danced and rattled death of the former. particular theme is the product of somebefore our senses as a result of the entirely wound -up energy source which graduallyautomatic workings of some unknown type Human Personality dissipates itself through one particular setof energy strain or complex in Time -Space. It may well be that the human personality,or pattern of intricate channels resulting Such a theory of ghosts dissociates all when loosed, either temporarily or perms:in the recurrent manifestations. spectres from supernatural attachments and nently, from the body, can thus bridge Space and Time and give rise to some sort of telepathic or televisionary manifestation of itself.The fact, also, that, in certain hypnoticstates,individualpersonalities have been more or less expelled from the body and have claimed to have visited other scenes lends additional colour to this " telepathic " theory of ghostly manifesta- SHORT tions. Although such a theory cannot cover CIRCUIT allaccreditedinstancesofhauntings, particularly those of a long-standing nature. An uncoilingspring it is one which must carry due weight in many given circumstances. These occurrences represent the Perhaps the second of the above general- dissipation of energy, or flow of ised explanations of ghostly phenomena is energyfrom high to low potentials. . the one which represents the best field in much the same for active theorisingandresearch. This is. manner according to a theory of course, the generalisation which accounts explained in this article, ghostly for ghosts and all related phenomena by manifestations are the result of definitelyassertingthattheyactually other energy -releases in Time - Water flowing from a high level exist externally in Time and Space and Space to low apart from the observer of them. That which may be termed the " super- " Physical " Theory from all volitional attributes. A ghost, in natural " theory of hauntings comes under There is, indeed, one theory of hauntingsthelightof thistheory, has no more this main generalisation.This theory has-the " physical " theory we may call itmind of its own than the actual black -and - it that ghosts, spectres, hauntings and all-which attempts to account for the factswhite image of a film actor flashed on to a associated manifestations are directly thein this manner. Such is the only " scienti-cinema screen. results of un-bodied intelligencesactingfic " thebry of ghosts which can be said to The energy complex which causes the upon or through the world of matter.hold any weight. ghost, says this theory, is closely associated This, perhaps, is the oldest theory of ghosts. According to this " physical " theory awith the material environment existing That such intelligences have been usuallysort of strain may be set up in Space -Timeat the time of its setting up. presumed to be evil ones, and that manyin much the same manner as a molecular In other words, murder a man inhis of the phenomena of spectral manifestationsstrain is created in the spring of a clockbedroom at the dead of night, and you are, to say the least, of an extremely child-orother mechanism when itis woundstand a chance of creating his ghost which ish and even an idiotic nature, cannot beup. may appear in the same room or, at least, cited directly against this theory. After all, Many different varieties of Space -Timein the same house for a couple of hundred ourstandardofso-called" normal "strains must be possible and, no doubt,years or so. But having thus brought into intelligence is merely an arbitrary, although,the gradual release of such strains underliesexistence (or pseudo -existence) his ghost, no doubt, a well-founded one, and it may,many of the curious happeningsin theyou can do away with it by pulling the in all likelihood, differ a good deal from theUniverse. house down, for, by doing so, you have intelligence standard of the unknown class Now, if the intelligence -principle departsdestroyed the actual material environment of other -world busybodies and mischief -from a human being under certain un-of the murder. And if, subsequently, you makers whose ghostly object is apparentlyexpected and usually sudden conditions, if,decide to build another house on the same that of striking fear and panic in the mindsfor 'example,an individualisbrutallysiteitis hardly likely that you will be of their human observers. murdered,it may be possible. that thetroubled with the recurrent ghost of your The fact that the ceremony of " exor-departing mind of that individual is ablevictim,forthespectrewas primarily cism," or the casting out of spirits, has beento set into existence certain energy patternshaunting his environment, not your own in modern timessuccessfullypractisedwhich, containing within themselves con-guilty individuality. as an aid to ridding a ghost -ridden dwellingsiderable vitality, form a source of potential A strange theory this, no doubt, and one from its recurrent manifestations certainlyenergy or force. which, with the methods of modern science, strengthens the " supernatural " theory of It is a well-known law of the Universecannot yet be proved. Yet it has its pos- such hauntings, but it in no way explainsthat all sources of energy tend to run them-sibilities. their meaning of their mechanism. selves down. The wound clock spring at all If, believing in or having had any first- Hauntings are repetitive in nature. Thattimes tends to become unwound.Heathand experience of ghosts,spooks and is to say, having once started, they tendenergy tends to dissipate itself.Electricalspectres, we can bring ourselves round to to recur at regularintervals. Anotherenergy invariably attempts to leak away.face the fact that such apparitions (if they curious fact about hauntings is that they areWater at high level makes every effort tohave any existence at all outside our minds) seeminglydependentupontheactualflow from that level.In a word, ,highmust necessarilyrepresentasourceof material surroundings or environment ofenergy potentials in Nature tend alwaysenergy, we shallhavethen based our the haunted area. 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EXAMINATIONS Technical, Professional, Matriculation, and Civil Service.State the one you wish to pass NOTE.-If your subject is not on the above list, write it here NAME Age ICS ADDRESS December, 1939 NEWNES PRACTICAL MECHANICS 119 Chemistry for Beginners No. 9.-The Study of Organic Chemistry. A Field of Engrossing Interest for Every Amateur matter.If, for instance, you stir the bed of a country pond, the bubbles of gas which will arise to the surface will contain a large proportion of methane. Now methane has theformula, C114, which expression means that it contains four atoms of hydrogen united to one atom of carbon.Actually, the hydrogen atoms of methaneare arranged symmetrically around the central carbon atom, so that the " structural formula " of methane is :- H H-C-

In the laboratory, it is quite easy to make methane simply by heating in a test tube a mixture of 1 part of anhydrous sodium or

Making methane or -fire-damp,- by heating a mixture of anhydrous sodium or potassium acetate and soda - lime, the evolved methane being collected over water in the usual mariner for gases

1I I:Nthe Science of was in its infancy just a little more than a hundred years ago, theoretical chemists considered that there existed a vast and fundamental difference betweenchemicalmaterialsofmineral origin, such as, for instance, sulphate of - iron,andthosematerialswhichwere derived from animal and vegetable sources, as, for example, quinine, sugar tannin, or fat. The latter substances, it was said, would never be capable of being produced arti- ficially in the laboratory since, for their formation in the plant or animal organism, a certain vis vitalis or " life-force " was necessary, a vital energy which was, of course, altogether absent from all laboratory operations. This theory, however, was eventually disproved in 1828 by the German cheinist, F. Wohler, who showed that an aqueous Making acetone by heating dry calcium acetate in a test tube, the acetone being solution of ammonium cyanate, which can condensed in another tube cooled in water be derived from purely mineral sources,together with oxygen and hydrogen, andpotassium acetate with 4 parts of soda lime. can, under certain simple conditions, besometimes nitrogen, sulphur, phosphorusThe evolved gas can be collected over water changed into one of the chemicals existingand a few other elements. in the usual manner, as depicted in the in the human and animal body. Obviously, Carbon, however, is, as mentioned previous.illustration accompanying this article. therefore, Wohler had succeeded in prepar-ly the one element which underlies all the Methaneisa colourless,invisible gas ing a " life " compound without the mediumknown organic compounds, of which, at thewhich is inflammable and burns with a pale, or intervention of actual life in any formpresent day, there must exist atleast anon -luminous flame.It forms a highly whatever. hundred thousand separate and distinctexplosive mixture when mixed with air or varieties. And the reason why carbon isoxygen,thischaracteristicof thegas Theory Abandoned so extraordinarily fertile in its production ofunderlying all the " fire -damp " explosions Thus it was that the whole previousthese almost numberless " organic " com-in coal -mines. theory ofvisvitalisgradually becamepounds is due to the fact that in some Now if,in methane, we substitute a abandoned,for,afterWohler'spioneerstrange and, as yet, not entirely explainedchlorine atom for one of the atoms of discovery, several other so-called purelyway, it is capable of linking up with itself,hydrogen, we obtainchlor-methaneor natural substances were prepared artifici-as it were, one carbon atom forming chainsmethyl chloride, CH3.C1.Substituting two ally in the laboratory. and linkages with other carbon atoms,chlorine atoms for two hydrogen atoms, we With theinvestigation andartificialwhich chains cap have numerous branchgetdi-chlor-methane,or methylenedi- preparationof thesenaturally -occurringchains, circular chains and so on, to whichchloride, CH2CL2. Three chlorine atoms materials, arose the nowadays far-reachingatoms of other elements may be attached. substitutedforthe hydrogen atoms in and overwhelmingly important science of methane gives tri-chlor-methane or chloro- " Organic " Chemistry, or, as we shall seeMethane form, the well-known anaesthetic liquid, later,the" ChemistryoftheCarbon The very simplest organic compoundwhilst, if we substitute all the hydrogen Compounds."For allthese compoundsis the gas, methane, which is, of course, the.atoms in methane by chlorine atoms we which were produced by " organisedformsdeadly " fire -damp " of coal -mines. Methaneobtaintetra-chlor-methane,or carbon of plant and animal life were shown toisalsosometimesevolvedduringthetetrachloride,thenowadays much -used contain fundamentally the element carbon,decomposition of slowly -decaying organicfire -extinguishing liquid. 120 N EVVNES PRACTICAL MECHANICS December, 1939 tone has the formula CH3.CO.CH3, and, when pure, it is a colourless liquid boiling at 56° C. When mixed with a strong solution of sodium bisulphite,itforms a crystalline compound-acetone sodium bisulphite-from which acetone may again be regenerated by distilling it with sodium carbonate. Aceticacid, which has the chemical formula, CH3.COOH, and whichis,of course, the acid contain° 1 in vinegar,is readily made in the laboratory by distilling anhydrous sodium acetate with sulphuric acid. Sodium acetate can be prepared by neutralisingstrong vinegar with sodium carbonate, and thus, by this means, pure acetic acid can be obtained from ordinary vinegar.The pure acid is a colourless, pungent -smellingliquidwhichboilsat 118°C. and freezes to a mass of white, ice - like crystals at about 12°C. Note should be taken of the fact that acetic acid is in- flammable at its boiling point. Acetylene Acetylene is still another simple organic compound whichis,perhaps, toowell- known to need description. By its prepara- Laboratory apparatus for making chloroform.Bleaching powder and water are distilled with tion from calcium carbide and water it is acetone or alcohol obtained in a fairly pure form and if the gasis passed into a solution of copper The following scheme of" structuralin and a mixture of chloroform, water andchloride, made alkaline with ammonia, a formulae" will render clearer the meaningalcoholwilldistilover,the chloroformbrick -red precipitate of copper acetylide is of the foregoing paragraph :- collecting as a heavy, almost colourlessformed.This material should never be H U U liquid at the bottom of the receiver. allowed to dry, since, when dry, it explodes on striking or when heated to about 120°C. H-C-H1 H-C-H1 H-C-1.51 Chloroform Sulphuric acid strongly absorbs acetylene The chloroform prepared in this way isgas, and when the resulting solutionis not perfectly pure. All the same it possessesdistilled, acetaldehyde, a liquid smelling Methane. Chlor-methane Di-chlor- the characteristic heavy, somewhat pleasantof apples, passes over. (Methyl methane smell of the anaesthetic.Its vapour, of Acetylene has the formula C2H2 and chloride) course, should not be breathed unduly. when, under certain conditions, it is heated dichloride) Another interestingto a dull red heat, a portion of it changes U U preparation in organicinto benzene, which possesses the formula chemistry is the pro -C6H6, threemolecules of acetylene con- duction of acetone,densing together to form one molecule of H-C-U U-C--U 1 0 benzene. 1 c - the peculiar -smelling U U celluloid -dissolving Now benzene, of course, is one of the most Tri-chlor-methane Tetra-chlor- 1-14" C C -1- liquid which is now-commerciallyimportantofallorganic (Chloroform) methane adays so greatly usedcompounds,sincefromitisprepared (Carbon tetrachloride). C ---C in the manufacturenitrobenzene, aniline and a host of other Long Names of aeroplane dopes,synthetic compounds. The amateur student of organic chemistry /\C -H andsyntheticvar- Nitrobenzene is prepared without diffi- nishes and lacquerscultyinthe home laboratory.All we should not allow himself to be frightened require for this purpose is a fairly capacious by the long names which he will inevitably C-- C\/ 0 of all types. a To make acetoneflask in whichisplaced a quantity of meet with in his reading of the subject. I 5-0-N A N-H benzene. Double this quantity of a mixture These names, although more or less entirely 0 on a small scale all I of equal parts of strong nitric and strong unintelligible to the layman, really reveal H we need do is to heat the inner structure of the compound. Such calcium acetate in asulphuric acids is now added to the benzene testtubeprovidedin the flask bit by bit and with constant names comprise essentially certain chemical it 1,H shaking.During the gradual addition of codes which are readily translatable after N with a suitable glass delivery -tube leadingthis acid mixture, the temperature of the the student has had a little acquaintance C benzene should be kept as low as possible withtheengrossingstudyoforganic down into a cooled chemistry, and, in reality, they are no more receptacle, where-by immersing the flask in cold water. c upon an almost col- After all the mixed acids have been added mysterious and ponderable than isthe to the benzene, the flask is fitted with an expression, " Deputy -Chief -Assistant -Secre- C -C ourless, inflammable tary -to -the- Council - for - the - Protection - of - liquid of characteris-upright or " reflux " condenser and heated National -Liberties." H H H tic odour will collecton a water bath at about 80° for three- H in the receiver. Ace -quartersof an hour.Afterwards,the Indeed, run that designatory title into H contents of the flask,after cooling, are one word, and you will make up a descrip- H/ poured into a large quantity of water in a tivetitleequally as forbidding as the basin. A heavy yellow oil will separate. longest of chemical terms. The chemical representa- This is impure nitrobenzene. It should be In an outline article such as this, it is tion of a molecule of thecollected and re -distilled,using, for this obviously impossible to describe more than - - H dyestuff,"brilliant Congo." purpose,not a water -condenser but an a very few organic preparations which can Itrepresents atriumph ordinary length of glass tubing which will be made in the home laboratory. Referring, N ofchemicalarchitecture act as an air-cooled condenser. however, to the above methane series of 11-1 and itisinterestingto compounds, perhaps the most practically N C- C Nitrobenzene compare it withthe Prepared in this manner, nitrobenzene interesting is the anaesthetic liquid, chloro- V \ formulaofthesimplest form,ortri-chlor-methane.This may C -H organic compound methane will be obtained as a heavy yellow oil readily be made by placing in a fairly large or "marsh gas" smelling strongly of almonds.It boils at flask connected to a condensing apparatus a C -C 205° C. and is miscible with most organic cream of water and bleaching powder H liquids, but is practically insoluble in water. (chloride of lime). About one -quarter of the H -C C -H Under the name of " Essence of Mirbane," bleaching -powder cream's bulk of methy- nitrobenzene,whichhasthechemical lated spirit is then added and the flask is --C-S/ -0-N° a formula, C6113.NO2, is used as a flavour subsequently very gently heated on the Qo and perfume for cheap products such as water bath. A vigorous re-actiowill set boot polish and certain disinfectants. December, 1939 NEWNES PRACTICAL MECHANICS 121 Alcohol is a typical organic liquid, sinceparticularinstance,sincethealcoholacetic acid. Add to this solution about a it is usually prepared by natural fermenta-actually combines with it. third of its volume of strong nitric acid and tion of sugar solutions. To prepare alcoholAlcohol heat the resulting liquid for half an hour (ethyl alcohol-C2H5.OH) successfully, all Ethyl alcohol, when pure or nearly pure,on a water -bath. On pouring the prpduct we need do is to make up a weak solutionisapleasant -smellingcolourlessliquidintowater,nitro -naphthalenewillbe (say a 5 per cent. one) of common sugarwhich boils at 78°C. and which takes fireprecipitated. It can be re -crystallised from and add to this one or two fragments ofwhen ignited by a flame.All its charac-alcohol or methylated spirit. ordinary yeast. When kept in a warm room,teristic properties are due to the -OH The secondof theabove -mentioned the liquid will soon begin to froth and to(or oxygen -hydrogen) group of atoms whichpreparations is that of iodoform, CHI3, the give rise to bubbles of carbon dioxide gasit contains. There are very many differentwell-known powerful antiseptic substance. owing to the yeast cells feeding upon thekindsofalcoholsknowntoorganiclodoform, CHI3,isstructurally akin to sugar in the solution and converting it intochemistry, but they all contain at least onechloroform, CHC13, but it contains three alcohol and carbon dioxide. of these -OH groups. Glycerine containsatoms of iodine instead of chlorine. After about twenty-four hours' time, thethree of these groups.Itis,therefore, liquid should be filtered and distilled untilessentially an alcohol-the alcohol of fats-lodoform about one-third of its volume has didtilledand it possesses the formula :CH2(OH). To make iodoform, gradually add 2 parts over. This latter distillate (as the distilledCH(OH).CH2(OH),a factwhichwellof iodine to 2 parts of carbonate of soda liquid is called) will contain practically allillustrates the chain -forming habits of thedissolved in 2 parts of water. Add 1 part of the alcohol. It should be placed in a cleancarbon atom. of alcohol or acetone and heat the mixture flask and lumps of fresh quicklime added to Finally,details may be given of theto about 700 C. for a quarter of an hour. it and allowed to remain in contact with itpreparation of a couple of well-definedIodoform will now separate out as a yellow forthreedays.Quicklime has a verysynthetical organic compounds which willprecipitate.It should be filtered off and powerfulaffinityforwater anditwillserve as good experimental exercises inpurified by re -crystallisation from alcohol abstract most of the water from the alcohollaboratory chemistry. or spirit. When pure, it is a yellow solid, mixture so that when the latter is again The first of these is nitro -naphthalene, amelting at 120°C.It has a very charac- distilled an alcoh ol of fairly high puritymaterialwhichcrystallisesinyellowteristic, penetrating and, to most people, will be obtained. crystals which meltat61'C. Nitro -not unpleasant odour and it is volatile in Anhydrous calcium chloride which is sonaphthalene is made by dissolving ordinarysteam.Owing to its powerful antiseptic often used for " drying " liquids in thisnaphthalene (the white, odoriferous materialproperties,iodoformismuch usedin manner,cannotbeemployedinthisfrom which moth balls " are made) insurgery and medicine at the present day. MAKING A PERSPECTOGRAPH A Device for Enabling Artists to Draw Buildings, etc., in Correct Proportion

THIS useful instrument will be foundof the rod, a thickening block, in. thick.nail.Cut off the heads of these nails, and a great aid to the sketch artist.It isis glued at the end of the bar. file the shanks to a point, thus forming a intended to be screwed to a tripod The rod is accurately marked into inchesspike to prevent the legs slipping.To the stand, and this is the way to use it.Fig. 1bylines scratched half -way round, i-in.tops fix a 2 -in. brass hinge. is a view of the instrument minus the stand;lines being a quarter of the way round, and Now mark out and cut the tripod top you will see it consists of a horizontal barthe On. lines being short cuts between. as shown in Fig. 5 using wood tin. thick. of wood with a vertical rod at one end and a The top crossbar is similar to the bottom,It should then be varnished. The instru- sliding view -point at the other.On theand should slide easily up and down thement can be taken to pieces and strapped rod are two crossbars, the top one capablerod. This can be effected by lining the holeto the tripod for easy carrying. of movement up or down the rod, and itselfwithapieceof fitted with two horizontal slides. cloth or rubber. Now, suppose you desire to sketch a The pattern for building of some kind, say, for example,the slides at each a church.Look through the eyehole, andsideisshown at arrange the height of the tripod until theFig. 3, which should edge of the lower crossbar coincides withbe cut in thin sheet what will be the baseline of your sketch.brass and bent to Slide down the top crossbar until its frontshape. The edge, edge appears to touch the ground line of thefacingtheartist, church. The rodis marked in quarterofthe crossbar inches, read off the distance between theshould be marked crossbars, and draw a line on your paperin quarter inches, Fig. 4.- this distance above the baseline alreadyand numbered in vo Details of drawn. Raise the crossbar to a level equalinchesfromthe the tripod to the roof of the church, then read off thecentre outwards. legs distance as before and draw the roof line on the paper. The View Point Support Moving the Slides This has a smallFig. 3.-The Movement of the horizontal slides willhole bored in, andpattern for the now indicate the width of the church, andisscrewedtoa slides the points on the roof where the steeplesheetbrassslide, rises from. The crossbar can now indicatebent to the shape the height of the steeple, and you will haveas in Fig. 2. Fig.1.-The the body of the building drawn in correct Bore a hole in the finishedinstru- proportions.Details are put in the samecentre of the main ment way, such as windows,etc. barfora tripod Hardwood is used for the work, 1 in.screw,and varnish. by + in. in section, the main dimensions Forthetripod being given in Fig. 1.The rod is a piecestand, cut three legs Fig. 2.-The of i in. or i in. dowel rod, glued in a holefrom wood Iin. view point sup- bored in the lower crossbar with an inchthick, to the size port projecting below; this is tightly fitted in ain Fig. 4, and at similar hole bored in the perpendiculareach of the lower SECTION OF bar. To provide a firm seating for this partends drive in a wire EYE HOLE 122 NEWNES PRACTICAL MECHANICS December, 1939 rusyInventors A third patent in the United States has Convenient for Callers been granted for an illuminated globe. THE sum total of all the time visitors y "Dynamo" This sphere is surrounded with a map of and tradesmen are kept waiting at our the world. A lamp within, shining through doors in a single day would, probably,while to apply for a patent. The new brandthe translucent wall of the globe, causes amount to one lifetime.I have seen pen-of stilts is less stilted than its predecessors,the countries of the earth to be exhibited cilled near an area bell this crude couplet: at least as far as portability is concerned.in various colours, as is the manner of " Gentle tradesman, do not weep ; They appear to be nearly related to themaps. This globe will teach the young idea They are not dead but gone to sleep." fishing rod. Each standard is hollow and into shoot as regards geography. It will also When one rings at a door and there is notwo parts, which can be joined together.enable the adultto examine thecon- immediatereply,theinclinationistoThe footrest is hinged, so that it will swingfiguration of those unhappy countries where assume that no one is at home.It mayupwardly from the, normal position. Theseaconsiderableamountofshootingis happen that the housewife is occupied withcompressible features enable the stilts to betaking place. some domestic duty which she cannot atpacked or carried with convenience, though the moment leave. Thanks to a new inven-the compass attainable hardly justifies them tion, the lady can press a convenientlybeing styled a pocket pair of stilts.ItMask for Motorists placed button, which lights a small bulb atshould be added that, when they are adjustedYET another protective mask is the sub- the front door. On this bulb is the wordfor use, a locking arrangement prevents the ject of an application to the British " Wait."Itis asserted that, to fix thissections from becoming unmated. Patent Office. This -time it is not designed device, only one wire need be added to the to guard us from the machinations of our regular doorbell wiring. Watertight Watch human foes ;it is intended more particu- By the way, in a suburb of London, a Switzerland,whoseinhabitantslarly for motorists, cyclists and ski -runners. man with a brush and a pot of black paintFROMhave for centuries been famed for watch-The mask consists mainly of two pieces of used to knock at a door. If it were opened,making, comes a watertight watch case.flexible transparent material, such as cellu- he inquired whether he could re -paint theThe purpose of the inventor has been toloid, joined by a seam. The upper portion knocker at the modest cost of one penny.contruct a watch case, in which the numberof the mask has a rim of a material qualified However, should there not be a response toof joints is so limited that the chance ofto provide tightness between the edge of his knock, he assumed that no one was atwater gaining admission is very remote. the mask and the skin. This material may home and robbed the house. Obviously water in a watch is not con-be plush or sponge rubber. In this connection, my mind goes backducive to the health of the works.I pre - Inside the mask, there is arranged above,: some years to a device which indicated the mouth and nostrils a partition, so as to whether an electric doorbell were function- prevent the upper part of the mask from The information on this page is specially supplied to becoming bedewed by exhalation.Other- ing properly. When one pushes the button, "Practical Mechanics" by Messrs. Hughes & Young if: the bell is out of reach of the ear of the (Est. 1829), Patent Agents of 9 Warwick Court, High wise the mask, like a motorist's windscreen, caller, there is no evidence as to whether it Holborn, London, W.C.1, who will be pleased to send would need a wiper. is in order. When this indicator bell push readers mentioning this paper, free of charge, a copy was installed, the visitor could tell if the of their handbook, " How to Patent an Invention." bell were not behaving correctly. Anti,00ze sume that, on an extremely hot day, theSEEPAGE, or the art of gently oozing, Noise Analyser average watch in the waistcoat pocket is not is a besetting sin of lagoons, reservoirs, impervious to perspiration. And this newsmall streams and of ditms made of earth, THAT industrial orchestra, whose musicinventionshouldmilitateagainstthewood and concrete.To counteract then, 1is the hum of machinery in a factory, isentrance of any kind of moisture. Lilliputian leaks, a new powder has been not invariably in tune. Unnoticed by the produced. This powderforms with ordinary listener, the discord of the irregu- water a gelatinous mass and fills voids in larity of rhythm is often apparent only toNo Admittance to Gas contruction materials. There are two kinds the trained engineer.But not even he AT the moment of writing, the noxiousof the powder. The first is employed where always detects a flaw in its incipient stage. gas menace has not materialised.But,the water can be drawn off. After draining, An apparatus has been conceived whichas unremitting vigilance in relation to thisearth construction is ploughed to a depth of can analyse noise in machinery.It is andanger must not be relaxed, an anti -gasa few inches. The material, spread in the electrical acoustical device, which at oncedoor which has been devised is appropriateproportion of 100 pounds to each 400 reveals abnormal sounds and informs theto our times. The object of the inventorsquare feet, is raked into the surface and machine minder that there is a defect inhas been to provide a swing door whichthen rolled. the mechanism, thus preventing a break.functions in the normal manner, but can The second typeisused whereitis down.It is stated that one manufacturerbe rendered gas -proof at a moment's notice.impossible to drain away the water. The of canned goods is using this noise analyser In an emergency, a tube can be inflated,powder is cast on the surface of the water. to discover solder pellets which may dropand, when the door isclosed, this tubeIt sinks to the bottom and fills the crevices in during the filling and sealing operations.expands to seal the entire space betweenand the points where the water would At this juncture I recall a near relative ofthe edges of the door and its surround. Theotherwise stealthily make its escape. thestethoscope which was announceddoor is formed with a cavity which houses a some time since to have been constructedpiston pump for inflating the tube. And by German technicians. The aim of thisthis gevice will, itis claimed, absolutelyA Full Crop amplifier is to detect the presence of woodrefuse admittance to harmful gases. AN appliancefor a patent relating to worms in trees before it is too late to save poultry food has been made to the the latter from destruction.It is affirmedTo Prevent "Housemaid's British Patent Office.I am informed that that, when the apparatus is held close to the feeding of fowls and other birds by the trunk of a tree, should wood worms Knee means of meal is not always economical. be present, their chewing can be heard as MONG recentpatents granted in theTo avoid waste, it has been usual to com- loudlyasthechoppingof wood-forAA,United States, I note a tree -climbingpress the meal into cakes or pellets. These - example, the sound produced by the Kaiserdevice comprising a frame adapted forhave generally been manufactured in ver- felling a tree on his estate at Doorn. attachment about the trunk and includingmicular form-that is worm-like-and cut penetrating teeth. This elevating inventionup into short lengths, so that each is in the Handy Stilts will enable one to be " up a tree," notform of a tiny cylinder. According to the above -mentioned inven- IN this country stilts serve only as a forminvoluntarily, but according to plan. of amusement. The ,circus clown vests Another American patentisstyled ation, meal is made up in the form of small them in flamboyant pantaloons which go" Kneeler bench." It includes a rectangularprisms of triangular cross-section.Itis to great lengths and give the impression ofwood strip, a cushion which consists of aclaimed that meal in this shape enables abnormal height. Somewhere in Germany Isoft, flexible porous rubber base secured tomore food to be taken into the crop, as believe the stilt once performed some usefulthe wooden strip and a thin, solid rubbercompared with the little cylinders.I infer office.Presumably there is a demand forlayer on top of the rubber base vulcanisedthat the prismatic form can be packed more these twin poles in the United States, sinceto the latter.Tahis device should preventtightly in the crop, which it seems itis some inventor there has thought it worth- housemaid's knee." desirable completely to fill. December, 1939 NEWNES PRACTICAL MECHANICS 123 "MOTILUS)1 PEEPS INTO THE MODEL WORLD

Around the Stores

ROUND about Christmastide I gener- ally make a tour of the London model shops-Hamleys, Bonds, Mills, Bassett-Lowke's, and the toy departments of the big stores like Selfridges, Harrods and Gamages-but I'm afraid thisyear displays will not be on such a large scale as usual, for London to -day is the scene of intensive air-raid precautions and the black- out rather limits visits, although I am glad to hear many of the cheap train excursions to the metropolis have been re-established. The finished " Mogul--an impressive model Therefore, I hope as many modellers as possible will try to make their usual Londonfromstarttofinishinthirtyhours already proving very acceptable to those trip.The model shops are still open, youTrix Trains who want to make their railway different know, and rely on your custom. In Hamleys I saw the Trix trains runningwithout adding overmuch to the cost. Well, Messrs. Trix, Ltd., are producing a limited number of the many novelties they had Here " Motilus" Brings you further News planned before the war, and the splendid range of their existing linesis available. and Pictures of Wartime Model Making Outstanding among these new items is the " Coronation Scot " presentation set fitted for remote control uncoupling, which was For instance the other day1 had aas merrily as ever, despite the black -out.illustrated in the October issue (now being pleasant surprise when calling in at Bassett-You can see them in many places and shopssold from stock). This month I am able to Lowke's at High Holborn to find they havein London.Last month I told you aboutshow you a photograph of their very attrac- placed on the market a really comprehensivethe new" Lowko " gradients, which aretive Pullman Car. The windows are glazed in transparent Celastoid and the caris designed to take lighting units and fitted for remote control coupling.Other attractive but not so expensive models are the L.M.S. and L.N.E.R. 4-4-0 locomotives, both scale models, the' L.M.S. designed as a Deely Compound, the L.N.E.R. a model of the \N ell -known " Shire " class.There are also the derelict hut, crane truck and crane with base to fit into, the system of the Many Ways Platforms. In response to the wishes of many owners and would-be owners who want ideas for their layouts, special blue prints which contain on them a tabulated

The T.T.R. Pullman Car set of parts for building a " live steam locomotive.In pre -pre-war days I believe they did sow 'thing similar in gauge 1, but this time they have adopted the more popular size of gauge " 0 " and have made itpossiblefor therelativelyunskilled amateur to build one of their popular- modern type -2-6-0 L.M.S. steam Mogul locomotives.The set of parts has many vital components-such as the boiler and cylinders-in. finished condition, and com- plete,consisting of over 50 parts costs £3 17s. (that is including the 10 per cent. increase due to A.R.P. expenses and the costoftheGovernment'scompulsory scheme for insuring stock against war risks). A fully descriptive booklet with good illus- trations is at present in the printers' hands and can be obtained, price sixpence.It is to be included, free of charge, in every set, and tells you how to complete the model Some of the parts used in the construction of Bassett-Lowke's L.M.S. steam " Mogul" 124 NEWNES PRACTICAL MECHANICS December, 1939 mum cost, for the drawings are only 1/- a sheet. This is something really ideal for the wintry evenings. Lead Figures Some years ago, Bassett-Lowke, Ltd., made up a series of famous passengers for gauge " 0 " railways.They included, if I remember rightly, Amy Johnson, George Bernard Shaw, Stanley Baldwin, Charlie Chaplin and Lloyd George, and had a very successful run among model railway enthusi- asts.I hear they are now reviving this idea and the first of their series is of course the Prime Minister, Mr. Neville Chamberlain, complete with his umbrella !He is now in stock and other figures of eminent states- men and heads of the fighting forces- Viscount Gort, Sir Cyril Newall, Evans of the Broke, Winston Churchill, are being produced in " model " form.In Bassett- The cut-out railway model of Roiert Stephenson's"North Star," painted and mounted on a wooden base Lowke's London shop is a very nice range of seamen of all periods to two different list of the amount of track, points, etc., hasPlywood Cut -Outs scales, and my photographs show other been drawn up.Even the complicated Readerswillremember theseriesoffigures constructed by the artist who is layout which Messrs. Trix, Ltd., showed atarticleswhichappearedin" Practicaldoing this work for Mr. Bassett-Lowke. the British Industries Fair this spring hasMechanics " in the summer of 1938 on " TheEvery figureis hand -made and displays been included, and the cost per print isProgress of the British Steam Locomotive "good accuracy and a high class of workman- ls. 6d. A list of the dimensions and typesillustrated by 13i m.m. drawings in outlineship combined with artistic merit. of layouts is obtainable from Bassett-Lowke,by Mr. E. W. Twining. There were thirty in Ltd. This is a step in the dir2ction of realall, containing in the series famous andWartime Models helpfromthe professional "totherepresentative locomotives since Richard I notice many of the shops are bringing amateur. Trevithick's Peny-Darren in 1803, Hedley'sforward their wartime toys and models and " Puffing Billy," etc., up to the present day here are two of the latest items of this New Zealand Centennial Exhibition It is hardly possible in peace time for me to get as far as the Antipodes and in war time I should say the chances are one thousand to one !But I am able to tell you about some of the attractive features of the New Zealand Centennial Exhibition, which, despite the war, opened at Wellington last month, and marks the completion of 100yearsofBritishSovereignty and organised settlement in New Zealand. The Department of Overseas Trade has natur- ally participated in this exhibition of a dominion overseas and has aspecially designedUnitedKingdom Government Pavilion. The theme is Commerce and Transport, and one of the notable exhibits illustrated in this space is a moving pano- rama of British Merchant Vessels, Which was originally shown at the Paris Exhibition of 1936, but has since been redesigned and brought up to date for the New Zealand Models of anti-aircraft units of the British Army display. The ships, which are accurate to a scale of 100 ft. to 1 inch, move at varyingI have heard from an artistic model makercharacter-anti-aircraft gun and searchlight speeds across a sea viewed through port-who has bought the complete series of blackon mobile chassis.The gun is a working holes symbolising the shell of a modern ship.line prints and mounted each locomotive onmodel in every sense of the word.It fires Representativeshipsof theMercantileplywood. He has fretsawed out the wooda wooden shell in manner similar to the full- Marine of over 20,000 tons built in Greatand finished the main outline neatly with asize machine.The barrel is elevated by Britain since 1926 are shown and thesefine file, then mounted each one on a slottedquadrant and pinion gears and traversing include vessels of the Canadian Pacific,base and painted it in natural colours. Hereby pinion and internal toothed wheel. The Cunard White Star, Orient Line, Penin-is a photograph of one done in this way andsearchlight, too, is a working model with sular and Oriental, Union Castle, besidesI think you will agree it makes a useful anda bulb to light up.It swivels on a turntable the new Royal Mail Liner Andes, the Shawcompact record of locomotiveprogress,on rubber tyred trailer chassis and four Savill Dominion Monarch, and, last, butbesides providing in the work skill for paint-levelling screws, the latter being used to not least,the new Cunard White Star,ing and at the same time making it possibleraise the searchlight from the wheels when in Mrtnretana. to have a set of these models at the mini-action.

Picturesque models of our fighting forces (left to right) R.A.F. pilot, R.A.F. pilot officer, the Navy, the Army (42nd Division Royal Artillery), 4th Hussars, the Queen's Bays, the 16 5th Lancers, the Royal Horse Artillery, the Scottish Clan Sinclair and the Macleod of Lewis December, 1939 NEWNES PRACTICAL MECHANICS 125 A DICTIONARY OF Metalsand Their Alloys (Continued from page 64 of last month's issue) Anatomical Alloy.-An alloy which is some- Ruolz in 1853.Very similar to silver in times used for taking casts of certain LIST OF ABBREVIATIONS appearance. Composition :Silver,20 The following abbreviations are used throughout portions of the human and animal body, this Dictionary : parts ;nickel, 30-75parts ;copper, such as an ear, after death.It melts at At. No. .. Atomic Number 70-75 parts. 169°F. and remains liquidat140°F. At. Wt. .. ..Atomic Weight Arguzoid.-A white nickel -silver metal of Composition: Bismuth, 53.5; lead, 17.0; ..Melting Point B.P. Boiling Point composition: Nickel, 20k; copper, 46i; tin, 19.0; mercury, 10.5 per cent. Sp. Gray... ..Specific Gravity zinc, 31 per cent.Used as a solder for Anka Steel.-A type of stainless chrom- Sp. Ht...... Specific Heat nickel silver articles. nickel steel containing about 15.5 per cent. Coef. Exp... ..Coefficient of Expansion Armco Iron.-A nearly pure iron.It con- of chromium and 10 per cent. of nickel. Therm. Cond. ..Thermal conductivity Elec. Cond. . ..Electrical conductivity tains under 0.1. per cent. of impurity. It is a well-known Sheffield steel. Arsenic.-Semi-metallic element, often Annealing.-The process of slowly cooling a referred to as a Metalloid. Chemical metal or alloy from bright red heat (or ous. When molten antimony solidifies, it symbol, As ;At. No. 33; At. Wt. 75 ; othersuitabletemperature) down to expands very slightly.Hence the metal Sublimes slowly without melting, but if ordinary temperature. It usually increases is useful in alloys such as type -metal, heated under pressure melts at 817°C. the softness and malleability of a metal. etc., from which fine and sharp castings Sp. Gray. 5.727 ; Sp. Ht. .083 ; Coef. Exp. Anodised Aluminium.-Aluminium which are to be made.Chemical science has .0000059 ;Elec.Cond.at0°C.(Mer- has been made the anode or positive shown that antimony can exist in several cury=1) 2.679.Chief Ores: Realgar, electrode of an electrolytical chemical different forms, such as yellow and black AsoS2; orpiment, As2S2; arsenical pyrites ; bath containing sodium phosphate or antimony (whichsee). The metalis mispickel ;mundic,FeS2.FeAs3. Also other solution.On passing a current attacked by most mineral acids and is occurs in free state.Arsenic was known through such a bath, the aluminium is chemically closely related to arsenic on to the ancient Greeks,its name being chemically oxidised on the surface, giving the one hand and bismuth on the other. derived from the Greek, arsenicon, mean- it a fine matt appearance. See Aluminium. It is used principally in the making of ing potent."Arsenic is a steel -grey Anticorodal.-A modern aluminium alloy of casting alloys. metalor" metalloid "which, when Swiss origin.Composition : magnesium, sublimed, forms lustrous hexagonal rhom- 0.6;silicon,1.0per cent.-remainder bohedral crystals.Like antimony, it can aluminium.It can be heat -treated and exist in several different forms or "alo- has a tensile strength of approximately tropicmodifications,"such as" Grey 20 tons/sq. in. Arsenic," " Yellow Arsenic," etc. (which Anti -friction Metals.-Name given to various see). When ordinarily heated, arsenic alloys which are employed for the pro- does not melt, but passes off as a garlic - vision of high-speed bearings.Owing to smelling vapour.Arsenic and allits the softness of the alloys, they stand up to compounds are exceedingly poisonous, frictionwell --hence the name " anti - but many of the latter are used in medi- friction "-and they are also able to with- cine.Chemically, arsenic is a reactive standheavypressures. A common element.As a metal, however, it is use- practice is to make the foundation of the less,except,perhaps,foralloyingin bearing of brass- or bronze and then to minutequantitieswith othermetals. linethis with the anti -frictionmetal. Thus, a trace of arsenic (say 1 in 1,000) in Thispracticehastheadvantageof lead makes the lead harder." Chilled enablingthebearingtobereadily shot " is usually hardened with arsenic. renewed merely by melting -out the anti - Arsenical Copper.-Copper containing small friction metal. amounts of arsenic.It has, in the past, Inthepreparationofanti -friction been employed for locomotive firebox metals,alloyscontainingcopper,tin, service on account of its supposed lower lead, antimony, zinc are used, but it is rate of oxidation.Recently, however, it seldom that more than three of these has been shown that the addition of metals enter into the composition of any arsenic to copper actually increases its one alloy. rateof oxidation,and nickel -silicon - Owing to the white appearance of these (Left) A rod of antimony.(Right) A rod of copper alloys have been introduced to anti -friction metals, they are frequently pure tin. The antimony is coarsely crystalline. replace it. termed " White metals." It will not withstand the slightest shock without Ashberry Metal.-A type of Britannia metal. Antimonial Lead.-Lead containing antim- breaking.The tin, being finely crystalline, will Composition :tin,80 ;antimony,14 ; ony. resist considerable strain without fracture copper, 2 ; zinc, 1; nickel, 3 per cent. Antimony.-Metallicelement. Chemical Ash Metal.-A very low-grade brass alloy symbol, Sb (from the Latin, Stibium).Aphtit.-An iron -nickel alloycontaining made from metal skimmings and ash At. No. 51; At. Wt. 120; M.P. 629.2°C. ; tungstenandcopper. Composition : from brass founderies. B.P. 1440°C. ;Sp. Gray. 6.7 ;Sp. Ht. Iron, 66 ; nickel, 23; copper, 5 ; tungstenAuer Metal. --An alloy of iron and cerium .0495 ; Coef. Exp. .000012 ; Therm. Cond. 4 parts. metals, similar to 'Mischmetal " (which (Silver =100) 4.03 ;Elec. Cond. at 0°CArdal.-An aluminium alloyofBritish see).It is a pyrophoric metal and emits (Mercury= 1) 2.05.Chief Ores : Stibnite, origin.Contains : Copper, 2 ;iron, 1.7; a bright shower of sparks when struck. 813283;antimonybloom,Sb203;and nickel, 0.6 per cent.-remainder alumin- Used in automatic lighters, etc.It was antimonyblend, Sb20.32S1)2S3. Also ium. introduced into commerce by Dr. Carl occurs in free metallic state.AntimonyArgasoid.-Animitationsilver. Com- Auer (later Baron Auer von Welsbach), was known in medieval times, its prepara- position : Tin, 4 ; lead, 3.5 ; copper, 55.5 ; the inventor of the incandescent gas tion being described by Basil Valentine, a zinc, 23; nickel, 13.5 parts; together with mantle. Hence its name. Benedictine monk, in 1413. The meaning a trace of iron. of the name " antimony " is not known,Argentan.-A nlekel or German silver. Austenite.-Name given to a solid solution but it has been supposed to be derived ArgentiferousLead.-Lead containinga of carbon in pure iron (" gammaferrite ") from the Greek, anti, against; nomos, the small proportion of silver, as it often Named after W. C. Roberts -Austen, the law. does in the natural state.(From the metallurgist.Steels, containing austenite Antimonyisasilvery -whitemetal Latin;.argentum, silver.) are termed " austenitic." having a pronounced crystalline structure.ArgentineMetal.-Abright -lookingtinAustenitic Steel.-See Austenite. 'Very brittle and easily powdered. A poor alloy sometimes used for making toys,Australian Gold.-The standard gold coin- electrical conductor.. Does not readily etc.Composition: Tin, 85.5; antimony, age of Australia (as minted at Sydney) tarnish in dry air, but becomes covered 14.5 per cent. contained 91.66 per cent. of gold and with a film of oxide in moist air.AllArgent-ruolz.-(Ruolz's silver.)A series 8.33 per cent, of silver, thus giving to the antimony compounds are highly poison- of alloys patented in France by M. de Australian gold coinage its characteristic 126 NEWNES PRACTICAL MECHANICS December, 1939 greenish -yellow appearance. In English cent. ; tin, 2.5 per cent. ; zinc, 7.1 per cent. per alloys recently introduced in America. standard gold the silver is replaced by Sometimes about .5per cent. of alu- Typical composition :silver,70.44 per copper. minium is also added. cent.; copper, 28.90 per cent. ; beryllium, Autogenous Soldering. -The uniting of twoBearings Metals. -See Anti -friction Metals. .87 per cent. Used as a resistance -wire pieces of metal together simply by meltingBell Metal. -A type of bronze or copper -tin. material. their edges by means of a blowlamp or alloy containing from 12 to 24 per cent.BessemerSteel. -Steel manufactured by other source of heat. The word " auto- of tin.Technically known as Hard the Bessemer process (the invention of geneous " means " self -generated." Bronze." Sir Henry Bessemer in1856). In the The lead linings of chemical and acidBeryllium. -Formerly named " Gluoinum." Bessemer process, the molten " pig " iron tanks are usually autogenously soldered Metallic element. Chemical symbol, Be ; is run into a receptacle known as a because the presence of any dissimilar At. No. 4 ; At. Wt. 9 ; M.P. 962°C. ; Sp. " converter," in which a blast of air is metal at the joints would set up electro- Gray. 2.1; Sp. Ht. .397. passed through it.Impurities are thus lytic actions which might attain serious Chief ore :Beryl, 3BeO.A1203.6SiO2. burned out of the molten metal. proportions. Occurs also in gems, such as emerald. BibraAlloy. -Composition :Bismuth, 8 Avional.-A Swiss aluminium alloy. Com- Name of the metal derived from its parts; tin, 9 parts; lead, 38 to 40 parts. position :Copper, 4.75 ; magnesium, 0.5 ; principal ore, beryl.Beryllium was firstBidery Metal. -An alloy which was at one manganese, 1.0 ;silicon, 1.4 per cent. ; isolated in an impure form by F. Wohler time very popular in India.It was first remainderaluminium. Ishardand in 1827. Not prepared in a pure, state manufactured at Bider. near Hyberabad, enduring. Tensile strength about 30 until 1885, and until very recent times it in India, from which town it takes its tons/sq. in. has remained an uncommon metal. Now- name. The metal does not easily tarnish adays,however,berylliumisrapidly or oxidize, and was at one time employed B attaining a status of commercial import- for the manufacture of Indian cooking Babbit's Metal. -The original alloy recom- ance, as a light alloying metal, particu- vessels.Its composition (average)is : mended by Babbit was made up of the larly in America. Tin, 1.4 per cent ; copper, 11.4 per cent. ; followingingredients :copper,4lb. ; Beryllium is a white metal resembling zinc, 84.3 per cent.; lead, 2.9 per cent. antimony, 8 lb.; tin, 24 lb.To every magnesium in appearance but being con-Billet. -A short, thick metal bar which is pound of the above, 2 lb. more of tin was siderablylighterin weight.Next to used for forging or rolling. added. lithium, beryllium is the lightest metal Many softliningand anti -friction known.Itisfairlymalleable,andBimetal. -Name given to two dissimilar, bearing metals have subsequently borne remains unchanged in ordinary air, even metals sweated or fused together so as the name of " Babbit," but the above is when heated. Powdered beryllium, how- to make up a composite metal sheet. the originalalloy devised by Babbit ever, when heated, burns much in the Nowadays, bimetals are much used in himself. same manner as magnesium, emitting a consequence of the unequal ratesof Bahnmetall.-" Railway Metal."A soft brilliant light. expansion of their constituent metals, bearing metal used on the German State Beryllium is acted upon by mineral causing the bimetal to curl when heated Railways for the linings of axleboxes. acids and bears a close chemical resem- and thereby enablinga temperature - Was introduced during the Great War blance to magnesium. It has now become measurement to be made or an electrical and is still used with, it is said, excellent an important alloying metal, and it may circuit to be opened or closed at a definite results.It consists of lead alloyed with yet be employed in the pure state in view temperature. small amounts of sodium, calcium and of its extreme lightness, provided that itsBinary Alloy. -An alloy pontaining two lithium.Approximate composition : manufacture can be cheapened sufficiently. constituent metals. sodium, .58 to .62 per cent.; calcium,Beryllium -Cobalt -Copper. -A high -conduc-Binary Steels. -These are alloy steels con. .59 to .73 per cent. ;lithium, .04 per tivity copper alloy, not unlike beryllium., taming one special alloying metal, as, for cent. ; remainder lead.It has a hardness copper,butcontaining.4percent. instance, chromium steel. of about 34 Brinell, and a compressive beryllium, 2.6 per cent. cobalt, balanceBirmabright.-An aluminium -magnesium strength of between 25,000 and 30,000 copper. Has an average tensile strength alloycontainingabout 7 percent. lb. per sq. in. of 95,000 lb. per sq. in. magnesium (and sometimes 1 per cent. Banka Tin. -Tin from the Island of Banka,Beryllium Copper. -A copper - beryllium of manganese). Can he worked easily and in the Dutch East Indies. alloy containing from 1.5 to 2.75 per is resistant to atmospheric tarnishing and Barium.-Metallie element. Chemical sym- cent. of beryllium, the standard alloy corrosion. bol, Ba ; At. No. 56 ; At. Wt. 137 ; M.P. having aberylliumcontentof 2.25.BirmailsSpecialAlloy. -An aluminium 850°C.Sp. Gray. 3.75 ; S. Ht. .068. Sometimes up to .5 per cent. of nickel is alloy containing from 10 to 13 per cent. First prepared (in an impure form) by added to these alloys to restrict grain size of silicon and from 2.5 to 3.5 per cent. Davy in 1808.Its name is derived from during annealing. They were originally of nickel, in addition to small amounts the Greek, baron, heavy, in reference to investigated by Dr. G. Masing in 1926 of copper, iron and manganese.It has the heavy mineral " barote " (afterwards and are now of much commercial interest. a good resistance to corrosion and a called" baryta ") which contains the In the annealed condition, the stan- high tensile strength.It is tough and element. dard beryllium -copper alloy has a tensile ductile. Chiefores : Heavyspar,Barytes, strength of 70,000 lb. per sq. in., whilst byBkmidiuni.-An aluminium alloy produced RaSO4, Witherite, BaCO3. Barium, when cold rolling and heat -treatment, its ten- in Birmingham. Hence its name. It has pure, is a silvery, lustrous metal, having sile strength can be still further increased. a composition and properties similar to ayellowtinge.Ithasrarelybeen The alloy is obtainable in rod, strip, sheet "Y" alloy, which see. obtained in the pure state,however, or cast form. It is now being much usedBirmingham Platinum. -A white brass of owing to the extreme difficulty of its forthe production of springs, which variable composition.The following is preparation.It tarnishes rapidly in air, show remarkable endurance properties, typical :copper, 43 per cent.; zinc, 57 becoming coated with a film of oxide.It and, also, for the making of non -sparking per cent.Also known as" Platinum decomposes water with the evolution of tools.With the gradual cheapening of hydrogen and the formation of barium metallic beryllium, beryllium copper Lead." This alloy was formerly used for hydroxide, Ba (011)2. alloys have a promising future. casting buttons. As a metal, barium has no uses what-Beryllium Gold. -Gold -beryllium alloys con-Bismuth Amalgam. -A thinly fluid amal- ever, although its chief ore, barytes, is of taining from .5 to 5 per cent. of beryllium gam prepared by adding 'mercury to great value in industry. Alloys of barium have been worked out in America. When molten bismuth. Almost any proportions with lead, aluminium, bismuth and anti- the beryllium content exceeds the former of these two ingredients may be used. mony have been reported from time to percentage, however, they become too Bismuth amalgams, on account of their time.Barium is closely related in chemi- brittle to work, the beryllium exerting fluidity are useful for filling very delicate cal properties to calcium and strontium. moulds.Other amalgams are also ren- an extreme hardening effect upon the dered more fluid by adding to them a Base Metals. -See Noble Metals. gold.Some of these alloys have been small proportion of a bismuth amalgam. Bath Metal. -An alloy which was at one used as gold solders and dental inlays. Bismuth amalgam is sometimes used time very popular in England for theBeryllium Silver. -An alloy of silver and forsilveringglass globes and similar manufacture of teapots, sugar basins and beryllium containing from .41 to .90 per articles. other tableware.It is silvery -white in cent. of beryllium. It has the remarkable Theamalgamwillpassthrough colour, and takes a high polish.Com- property of remaining untarnished in chamois -leather like mercury. The drops, position: copper 55 parts ; zinc 45 parts. atmospheres charged with sulphur com- however, are pear-shaped and not per- Baudoin'sAlloy. -Animitationsilver. pounds which would rapidly blacken pure fectly globular as in the case of pure Composition :copper,72percent.; silver. mercury. nickel,16.6 per cent. ;cobalt,1.8 perBermylliu-Silver-Copper.-A group of cop- (To be continued) December, 1939 NEWNES PRACTICAL MECHANICS 127

FOR ACCURATE WORK AND PERFECT FINISH A " M I LN ES " LATHEis Essential CHEMISTRY

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The facts of Le-incorporateallthe good points of the noir's early careerengines of previous inventors and possess can be related verynone of their very numerous drawbacks. briefly. He was bornTo this end, gathering to himself a little in the year 1822 atassistance, financial and mechanical, he was Mussy laVille,asoon devoting all his energies. small Belgium vil- Several gas engines were built in Lenoir's lage. His parentagetiny workshop until eventually one was was honestbutdesigned which he considered to be a humble, and he re-practicable and a marketable proposition. ceived a very sparse In 1859 Lenoir formed his first Company education.At thefor the commercial manufacture of his new age of sixteen, hegas engine. Under the name of Societe des left Mussy la VilleMoteursLettoir,the Company had a capital and journeyed toof two million francs,the works being Paris, there, he said,situated in the Rue de la Roquette, in Paris. The first Lenoir gas -engine patent for an engine dilated by the combustion of . gas " was taken out in France on January 24th, 1860. On April 17th of the same year, One of the first a complete French patent was obtained. Daimler cars fitted whilst a very similar one was granted tc withaminiature Lenoir by the British Patent Office on Otto four-stroke February 8th, 1860. gas engine First Gas Engines Lenoir's first gas engines were of the " stationary " type. Fundamentally, there IN the annals of French engineering, theto "make good in the world."Arrivedwas nothing really new in Lenoir's designs. name of Etienne Lenoir occupies ain Paris in the early part of 1838-justRather, Lenoir had proceeded according high and important position.It is, ofover one hundred years ago, by the wayto his intention of welding into a complete course, untrue to state that he actually-Etienne Lenoir obtained a job in anand satisfactorily working whole the good invented the first working gas engine, forenamelling shop. Out of his meagre earnings,points of previous inventors. gas engines, good, bad and indifferent-he scraped enough money to attend classes Virtually, the Lenoir gas engine was very mostly the two latter-had been createdduring the evening, and in this way he grad-much like an Ordinary high-pressure steam by various individuals during the early andually completed his neglected education andengine, except that it had valves to admit middle portions of the last century. Lenoir,taught himself the rudiments of science andboth gas and air and to release the products however, deserves the title of " Father ofmechanics. of combustion. the Gas Engine " which has been bestowed The piston of the 1860 Lenoir gas engine upon him with almost universal accordHis First Invention was driven forward for a portion of its since it was he who raised this type of prime The art of enamelling is, of course, anstroke by the inertia of a very large and mover from its experimental stage andancient one.It seems to have fascinatedheavy flywheel.At the same time,it placed its design and production upon aLenoir, for he studied the details of this artsucked into the cylinder a mixture of air satisfactory commercial basis. with much intensity, so much so that it wasand gas at normal atmospheric pressure. It is, indeed, to Lenoir that we owe ournot very long before he was able to bringthere being no attempt to compress this first industrial gas engines.The first ofout a new and easier method of fixing whiteexplosive charge. these engines which were made successfullyenamel on the dials of clocks and watches. The valves of the cylinder were then in England were turned out under Lenoir's This was Lenoir's first invention.Heautomatically closed, whereupon an electric patents, and although they were possessedseems, however, to have made but littlespark,derivedfrom a battery -operated of disadvantages which now seem almostout of it, for we next hear of him experi-spark -coil, exploded the mixture thereby ludicrous they initiated in Britain the eramenting with a system of electric brakingcausing the piston to be driven along the of the gas or explosion engine which sub-of railway trains and, also, of electricalcylinder to the completion of its stroke. sequently underwent an enormous amountrailway signal control.These activities,The products of combustion within the of development through the stage of thelike those of his enamelling career, did iaofcylinder were automatically exhausted on a four-stroke gas engine to the modern dieselbring him any material satisfaction.Heprinciple similar to that of the steam engine, and semi -diesel engines. relinquished them, therefore, and settledwhereupon the inertia of the flywheel took down in the machinery trade, starting forcharge of the piston's movements until the Little Known Career himself a diminutive workshop in a suburbnext firing spark occurred in the cylinder. in consequence of the activities of sub-of Paris. Lenoir's first gas engine was of 3 horse- sequent inventors who have improved the At this time, that is to say, during thepower. Despite the fact that it was rather original type of gas engine almost out of allearly " fifties " of the last century, thewasteful of fuel, it was smooth and relatively recognition, the career of Lenoir is nowa-subject of gas engines was very muchthesilent in action, and, structurally, it com- dayslittleknown. Of a modest andthing " in engineering circles. As we haveprisedathoroughlysoundmechanical retiring disposition, Etienne Lenoir seldomalready seen, a number of engines drivenproposition. sought a place in the limelight, and historyby the combustion of air -gas mixtures had seemingly has dealt with him according tobeen devised, but none of these had proved400 Engines At Work this characteristic, for, apart from a certainsatisfactory. Jn 1865, there were no fewer than 400 amountofenthusiasmconcerninghis Lenoir engines at work in Paris alone, inventions which crops up now and againHis First Company driving lathes,printing machinery, saw- in French engineering circles, the life and Lenoir,atthisperiodof hiscareer,mills, pumps and other varieties of mechan- activities of Lenoir are little known else-became greatly attracted by the prospectical appliances, whilst in England an al most where. of devising a gas engine which wouldsimilar" attackon industry had been made 130 NEWNES PRACTICAL MECHANICS December, 1939 by the English Lenoir interests, whole The Franco-Prussian war of 1870-71had enunciated the basic principles of a factory had been established at Reading. completely suppressed the Lenoir interestsform of gas engine in which four cycles of Besides being the creator of the firstin Paris.Lenoir, however, rallied to theoperations occurred, these operations com- commercially successful gas engine, Lenoirservice of the hard-pressed French Govern-prising the nowadays well-known cycle of must also be accorded the honour of beingment. He remained in Paris through thesuction,compression,ignitionandex- the first individual to run a road carriagehistoric siege of that city by the Germans,haustion of the cylinder charges. by means of a gas motor. and was subsequently naturalised a French- Proving that Dr. Otto had built up his Lenoir's claims to the invention of theman for his services during that hour offamous four-stroke engine upon Beau de earliest form of " motor car " have beentrial. Rochas' patentedprinciple,the Lenoir much overlooked, mainly in consequence - interests were able to hold their own and to of thestrikingsuccess of the GermanLenoir's Award claim that it was, indeed, the Otto patents inventors in this line.There is, however, Ten yearslaterLenoirreceived thewhich should be annulled. no gainsaying the plain fact that in May,award of the French Legion of Honour, 1862, Etienne Lenoir fitted a portable gasnot, however, for the invention of his gasFamous Legal Action engine to a heavy road carriage and, afterengines,but,ratherstrangely,incon- This, actually, is what took place as a numerous alterations and readjustments ofsideration of a minor invention of hisresult of the famous legal action. Lenoir's design, at last succeeded in driving thecomprising a system of telegraphy by meanspatent was upheld and the Otto patents carriage from his Paris works to Vincennes.of whichlettersandcharacterswerewere quashed. Hence, at a stroke the Otto This fact has been officially credited by theinscribed on a moving tape. monopoly fell to the ground and it there- Automobile Club of France, and it, there- Here, of course, Etienne Lenoir appearsupon became legal for anyone to make fore, constitutes a definite milestone (noas one of the early inventors of our nowa-four-stroke engines without licence from doubt the very first one) in the history ofdaysmuchcommerciallyused" tapethe Otto Company or its agents. automobilism. machine." In fighting this important patent action, The gas engine which Lenoir fitted to his This invention, however, brought littleLenoir undoubtedly helped on the coming first car appears to have been a ratheror no profit to Lenoir. He sold it, and,of the motor car, which came into practical strange one. The maximum " revs." of thewith the proceeds, devoted himself to theexistence soon afterwards. Any individual engine were only 100 per minute, and, asfurtherance of hisearlier love-the gasinventorcouldthereafterdesignand the engine was provided with a huge andengine. construct a motor vehicle for himself and weighty flywheel, its speed was correspond- In 1883 Lenoir invented a new form offit into it a petrol engine operating basically ingly slow. The maximum speed of thisgas motor in which he utilised the four-upon the four-stroke principle. Thus it was first Lenoir vehicle seems to have averagedstrokeprinciple. Theenginewasanthat an enormous impetus was given in all about three miles per hour (breakdowns notextremely economical one, so much so thatcivilisedcountriestotheinventionof included). it caused quite a sensation among the gaspetrol -propelled vehicles, an impetus which Obviously, the Lenoir type of gas engineengine -makers of the day. fructified in the rise and progress of many was hopelessly unfitted for portable use. variedtypesofmechanically propelled And, perhaps, because of his inner realisa-The Four -Stroke Principle carriages during the early " nineties " of tion of this fact, Lenoir soon lost interest Lenoir'sutilisationof the four-strokethe last century. in this side of his mechanical activities. Heprinciple in his new engine brought him at Despite his activities and his commercial sold his "mechanical carriage " patentsonce into directconflict with the Ottoinventions, Lenoir never became a rich to the French Compagnie Parisienne duinterests, of Germany, whose patent rightsman. Rather, he was always endeavouring Gaz in 1863. The latter concern, howeverhad, at that time, still some eight years toto ward off the spectre of poverty which made little use of them. run. The consequence' was that the Ottoever seemed to follow in his footsteps. This faction sued Lenoir for infringement ofwas, no doubt, on account of the fact that Powering A Motor Boat their master patents. A battle royal tookLenoir was not endowed with a businesslike Almost immediately afterwards, Lenoirplace in the French courts between the rivalsense. He parted with his patents too easily, experimented in the production of a gasfactions. For a time, the Otto camp seemedselling them at a very low figure, and engine suitable for powering a motor boat.to be heading for victory.It was proved,spending considerable sums of his own This creation held out better prospects.however, that the Otto four-stroke principlemoney on further mechanical experimenta- Referring to his 2 h.p.motor -boatgaswas fundamentally based upon the patenttion and research. engine, the inventor relates :- of aFrenchengineeringtheorist,one Indeed, had it not been for the Compagnie I obtained much better reiults with theAlphonse Beau de Rochas, who, in 1862,Parisienne du Gaz,of Paris,Lenoir, no doubt, would have died in extreme poverty. motor fitted into a boat.This proved the Ihn best' testing bench.' Another advantage As it was, however, this famous French was that I did not have to carry any water, concern allowed the inventor a small regular and this reduced the weight of the engine THE P.M.LIST OF income upon which, in his later years, he considerably. BLUEPRINTS had solely to live. ' In 1865, I made a 6 h.p. motor for F. J. CAMM'S PETROL -DRIVEN In Retirement Monsieur Dalloz, editor of the Moniteur MODEL MONOPLANE About 1890, Lenoir, then fast approach- Universel.This was fitted° into a boat 12 7s. 6d. per set of four sheets, full-size. metres long, but the speed was insignificant The "PRACTICAL MECHANICS" E20 CAR ing the allotted " three score years and (Designed byF.J. CAMM) ten " and being not a little disheartened and owing to the slow -running motor, and we 10s. 6d. per set of four sheets. disillusioned by the meagre and cheesepar- used far too much essence of petroleum." "PRACTICAL MECHANICS" MASTER ing treatment which hisinventionshad Lenoir's reference to not having to carry BATTERY CLOCK received, retired to a small villa on the river water refers to the fact that his ordinary BlueprintIs. gas engines ran exceedingly hot, and that The "PRACTICAL MECHANICS" OUT- Marne at La Varenne-Saint Hilaire. Here BOARD SPEEDBOAT he remained inretirementuntildeath they required large amounts of cooling 7s. 6d. per set of three sheets carried him away in the year 1900 at the water, a fact which militated against their A MODEL AUTOGIRO considerable age of 78. successful use in road vehicles. As motor- Full-size blueprint, Is. boat engines, however, they could be cooled SUPER -DURATION BIPLANE At the time of his death Etienne Lenoir adequately by means of river water. Full-size blueprint, Is. had been more or less completely forgotten The P.M. "PETREL" MODEL in the influx of motor -car and gas -engines MONOPLANE inventions which came around that period. "Essence of Petroleum" Complete set, 55. It was, indeed, only when a Lenoir com- The I-c.c. TWO-STROKE PETROL ENGINE It should be noted, also, that Lenoir, Complete set, Ss. memorative plate was ceremoniously un- in the above -quoted passage, refers to his STREAMLINED WAKEFIELD veiled in the Paris " Institute of Arts and employment of " essence of petroleum." MONOPLANE -2s. Trades " (Conservatoire des Arts et Metiers) This constitutes one of the very earliest A LIGHTWEIGHT GLIDER in 1912, that the true memory of the man references to the use of petrol for gas - Full-size blueprint, 2s. and his inventions returned. engine purposes. MODEL DURATION MONOPLANE Full-size blueprint, 2s. To Etienne Lenoir, " Father of the Gas Naturally enough, the Lenoir interests WAKEFIELD MODEL Engine," engineering in general owes a debt experienced "a great deal of open hostility Full-size blueprint, 2s. which it should not lose sight of.For if from makers of steam engines. Owing to the "FLYING" LOW -WING PETROL MODEL Lenoir had not lived, gas -engine develop- factthattheLenoir engine consumed PLANE ment might have been much different from lubricating oil abundantly, and generated Full-size blueprint of wing sections, 6d. and much slower than its progress, which an excessive amount of heat, it used to be LIGHTWEIGHT DURATION MODEL took placeatLenoir'shands.Indeed, said in a vein of much sarcasm that " The Full-size blueprint, 2s. The above blueprints are obtainable post free from without Lenoir, gas -engine design might Lenoirmotorisself-heating-and oil - M ess rs.G.Newnes Ltd.,Tower House,Strand,W.C.2 have been delayed by a quarter or a century

eating ! " IMO or even more. December, 1939 NEWNES PRACTICAL MECHANICS 131 Two FmousTrainin OOP Ships By"Seafarer" Famous Ships which Give the Budding Sailor the Finest Possible Prepara- tion for a Sea Life

H.M.S.Worcester" and Cutty Sark -

Looking astern from thefo'c'sle head of the "Cutty Sark," showing one of the anchors in the foreground The hew of the H.M.S. "Worcester" showing the old figurehead of the -Frederick William" Franco-German .war, were like.The Catty Sark's old 'tween decks have been con- verted into a main deck extending the THE Thames, fromits Source toitsgloriousafternoon when we arrivedatwhole ship and lighted by 36 scuttles, a mouth, is probably the most fascinat-Greenhithe station and wended our wayspace which is a very useful addition to that ing river in England, passing as itthrough the picturesque streets of the oldavailable in the Worcester.Readers will does through the greatest city in the world,town. Greenhithe has an historical interestremember the famous grain races of the andcombiningbeauty,industryand in being the port from which the explorerclippers home from Australia and China, romance. and navigator John Franklinsailed onin which the Gutty Sark played no small Itbears many ships whichgivetheMay 18th, 1845, for his last tragic voyagepart (running home from Shanghai on one budding sailor, whether for the Navy or thein command of the Erebus and Terror tooccasion without her rudder, which had Merchant Service, the finest possible pre-search forthe North West Passage. Ibeen carried away in a terrific gale)-so it paration for a sea life.Above bridges therecalled, too, as we left by motor boat fromis not surprising to learn that the plans to Navy League has its training ship Stork,the old quay that Franklin had foughtwhich she Was constructed were intended while lower down the Warspite, Exmouthunder Nelson at Trafalgar. to make her beat all sailing ship records in. and Triton render good service to the lower speed and seaworthiness. She was built in deck and forecastle hands. But perhaps theThe " Cutty Sark " Dumbarton in 1869. mostinterestingofallistheH.M.S. Our first visit was paid to the Catty Sark. Worcester moored off Greenhithe, famed forThis fine old clipper bears the same relation,The " Worcestet " the turning out of fineofficersfor theI should say, to the _Merchant Service, as Leaving the Catty Sark our motor boat British Merchant Service.Recently to thethe Victory does to the Royal Navy. Shetook us on to the Worcester.Like many. Worcester has been added the Catty Sark,was presented to the College in 1938 byother London shipping benefits, this vessel mast famous clipper of all times, and theseMrs. Dowman, widow of the late owner, toowes her being to the famous " Dickie " two ships, together with magnificent playingbe used in conjunction with the WorcesterGreen of Blackwall, though from the very fields on shore and the beautiful ingressfor the training of cadets, and classes arebeginning he worked in collaboration with Abbey (which is built from the stones of oldsent overtoher dailyforinstruction.William Bullivant, inventor of the modern London Bridge), make an excellent trainingFortunately the ship retains all her sea-wire rope and himself an old ship's officer. establishment for the Merchant Service. going appliances such as anchors, windlass,This was in 1861, when the disappearance holds, steering gear, life boats in davits,of the old East Indiamen had made it A Special Visit as well as a complete set of sails anddifficulttosecureatype of Merchant As a member of the Ship Lovers' Societyrunning rigging.It is a great pleasure toservice officer approximating to the naval 1 took the opportunity the other day, inknow that this vessel has been preservedofficer. The training ship Conway had been company with other kindred spirits of payingin its original form so that peoplecan knowestablished on the Mersey in1859, and a specialvisitto both ships.It was awhat ships built in 1870-the time of theLondon shipowners were determined to do 132 NEWNES PRACTICAL MECHANICS December, 1939 just as well or better on the Thames. Afterthe frigate's name, and is the present train-engines andboilers removed-and wa some discussion the Admiralty lent theing ship. towed round to the London river to be 50 -gun frigate Worcester, a ship of 1,500 This second Worcester was laid down as aconverted into the training ship, which she tons by the old measurement, and the74 -gun. sailing line -of -battleship in1833.remains to -day, smart and tight despite her venture was inaugurated in August, 1862, Her name was to have been Royal Sovereign,somewhat unpromising career. with 14 cadets. To begin with, the Worcesterbut the Admiralty decided to honour a When we paid our first visit naturally the was moored off Erith, but when it wasHanoverian prince and Royal Frederick wasships were untenanted and we had ample decided this locality was unhealthy shethe name -to -be.However she remainedopportunity of inspectingallpoints of moved to Southend for some years, thenon the stocks another twenty years andinterest. The gun ports are now fitted with up -river again to Greenhithe where she nowfinallywas launchedastheFrederickwindows and the lower decks used for is. William in 1860 ! accommodation for the students. But the The Admiralty, prejudiced against the old cook's gallery still remains and they Merchant service and the Royal NavalPioneer on the Thames still use the old coal fire cooking range. In reserve inthe last century, gave tardy This same year produced the ironcladcontrasttheshipcontainsthelatest acknowledgment to this work, but shippingWarrior, a pioneer on the Thames whichnavigationalinstruments,wirelesstele- companies soon appreciatedtheofficersrenderedall wooden - line of battleshipsgraphy, etc.-in fact ancient and modern turned out by the Worcester and the originalobsolete.For this reason the Frederickcombined.The presentWorcester -4,725 very modest scheme had to be changed toWiliam was completed slowly, did work astons displacement, length 214 feet, breadth meet demand. The old frigate was too smalla guardship in the River Shannon, and later60 feet-is the largest wooden ship afloat. and after much discussion the Admiraltywas paid off into the reserve at Portsmouth.These ships, I might add, are only open to exchanged her for the two decked line,of-It was not until 1876 she was lent to thevisitors by specialpermission, which is battleship Frederick William, which tookThames NauticalTrainingCollege-hermost probably withheld in wartime.

A shallow glass topped box is shown and the performer states that it can judge one's MAGIC WITH CHEMICALScharacter and foretell future events. Taking a piece of writing paper, he invites a member Amusing Tricks which will Provide Plenty of Fun at Xmas of the audience to breathe upon it.The THERE arethreepolymeridesoftrated sulphuric acid on a slab.With apaper is then laid in the magic box. In full acetaldehyde. One of these polymers,glass rod, spread this mixture on the surfaceview of watchers, lines of handwriting are metaldehyde,awhitecrystallineof a mirror in the form of some design-seen to appear on this paper which is then compound, sublimes on heating, giving offa face, a name, writing, or anything elsepassed round for examination, and is voted clouds of feathery crystals and the notyou fancy, but be careful to avoid bodilyan accurate character delineation. unpleasant odour of paraldehyde. This iscontact with the paste, which is of a highly Now for the construction of this wonder- thesecretofthedrawing -roomtrick,corrosive nature.After a few minutes'ful oracle. Obtain a shallow cardboard box wherein a tiny pellet placed on the glowingcontact with the mirror, wash the pastewith a hinged lid. Cut a large rectangle out end of a cigarette fills the air with " snow."away. When dried and polished, the mirrorof the latter and back it with a piece of The pellet is, of course, compressed metalde-will appear unchanged, but if you breatheglass, using Seccotine adhesive. A card- hyde, which is also sold in sticks under thegently onit,the design will stand outboard tray is now cut to fit inside the box the name of " Meta " solid fuel, a well-boldly.It is important that the fluorsparloosely, and itis supported by wooden known substance intended as a substitutepaste is not in contact, with the mirror tooblocks at each corner which give a clearance for methylated spirit.If you place half along,otherwise the designwillbeper-between box bottom and tray of about stick of this on a hot shovel, it will sublimemanently visible. in.Your magic box thus has a false completely, and in doing so willproduce In a similar way you can etch on glass.bottom, the apparent bottom being a loose enough " sham snow " to fill a large hall.Coat the glass with melted paraffin wax,fitting tray. To prepare it for use, remove For a less lavish display, a small corner ofand when it is set, scratch it away with athe tray and place a small tin lid containing a " Meta " stick on a lighted cigarette endneedle in the parts where you intend thea few crystals of iodine in the box bottom. will prove very effective. etching to take place. The fluorspar pasteReplace the tray which, being a slack fit, It is interesting to observe the progressis now applied to these exposed patches,allows the iodine vapour to fill all the box. of the sublimation process on the surfaceand left in contact for about ten minutes. The paper is next prepared. Make a little of thecompound.Colourless,featheryAt the end of this time, the paste and thestarch paste and thin it with water until crystals appear as if from nowhere. Theywax are removed, leaving the completeyou find that itis sufficiently thin to be cling to the surface, and to one another,etched design. used with a pen as a writing ink. As you are forming a long chain which, being very sure to know many of those likely to be light, grows upwards like a tree. In a stillHow to Make Ice Flowers present at your performance, it will not be atmosphere this " tree " will attain a height At this time of the year thereis nodifficult to write out the main points in their of three or four inches before breaking updifficulty in making Ice Flowers.Obtaincharacter, nor will it be difficult to state a into " snow flakes." three drachms of gelatine, soak it in waterfew very obvious future happenings. Men- untilit swells, pour off, and squeeze outtally give each intended victim a number Parlour Lightning adherent water and dissolve the gelatineand write this number in small figures on a This is also known as "Flash Paper,"in about a pint of warm water. Pour thiscorner of the corresponding paper which and consists of a thin square of nitratedsolution into a shallow tray, and leave outyou have written out for them.The starch paper which, when ignited, burns immedi-of doors during a frosty night on a flatsolution is of course quite invisible when dry. ately and completely with a bright flash.surface. In the morning the surface of the The performance of the trick needs no To make it, steep a few squares of thinsolution will be frozen. This is ice, the frostskill whatever. The starch in contact with typewriter paper in a mixture of three partshaving separated the dispersed phase (gela-the iodine vapour forms starch iodine which fuming nitric acid and one part concen-tine) from the continuous phase (water) inis a blue compound ; that is how the writing trated sulphuric acid. This mixture must bethe colloid suspension you left in the tray.appears. made verycautiouslybyaddingtheRemove the layer of ice by washing it sulphuric acid very slowly to the nitricgently with methylated spirit, when the acid and stirring all the time.Itis angelatine is exposed, woven, and spun into a extremelydangerous,fuming,corrosivethousand designs which resemble foliage WORKSHOP CALCULATIONS fluid, and the steeping operation is bestand flowers. conducted out of doors.At the end of To preserve this most interesting record TABLES AND FORMULIE twenty-four hours' immersion remove theof Jack Frost, flood the gelatine with a papers from the bath on a glass rod, washsolution of potassium bichromate and set by F. J. CAMM them until free from acid (test for this withaside for ten minutes. Pour off the solution, .1 handbook dealing with methods of calculation, solution to workshop problems, and the rules and blue litmus paper) and allow them to drywash the gelatine with a little water, dry. formulae necessary in various workshop processes. slowly without heat. The paper has nowand expose to sunlight for an hour.This It contains all the information a mechanic normally lostits former texture and taken on arenders thegelatineinsoluble,and the requires. tough, leathery appearance. When ignitedrecord is thus permanent. it will burn instantly with a flash. From allbooksellers,3/6net, A Chemical Oracle by post 3/9 from the publisher : A Retentive Mirror This entertaining piece of apparatus will GEORGE NEWNES LTD.(BookDept.), Obtain a little fluorspar (calcium fluoride)take little making and is capable of pro- Tower House, Southampton St., London, W.C.2 and make itinto a paste with concen-ducing much fun. December, 1939 NEWNES PRACTICAL MECHANICS 133 Buried Alive in the Boys! Ocean -Bed.. You can make real BRICK

Down in the depths a diver was facing death in its and MORTAR most terrible form-he had been boring a tunnel in the sea-bed when its walls had collapsed and Buildings with entombed him !Read how he faced the situation. Read ofthe photographer who went alone into the swirling BRICKPLAYER gas of a filled gasholder to try to get pictures.

Read of buried miners who had a stand-up fight after apit explosion because one man insisted on singing hymns. Read of the lumberjack who swam under a mountain to dynamite a log jam.These stirring true episodes are in:- ROUND THE WORLD IN INDUSTRY By Gerald Collinscf. wir net. BRICKPLAYER is not a toy,buta constructive and useful outfit with which to make real brick and mortar buildings. ROUND THE Above are only a few inci- WORLD IN dentsinthe livesof the Think of it! You can build your own railway arches, bridges, INDUSTRY world's daring workers-the stations, platforms, castles, houses, churches, villages, forts; GeltAtilCOLLINS men whose efforts ensure that you earn your living, infact, the listof buildingsis only limited by your own but whose bravery goes ingenuity. And what's more, each model has permanent unsung.This is a book you utility, because once the mortar is dry the building sets will read over and over again, for it tells you of these solid and will stand any amount of use-yet it can be easily work -a -day heroes, and the dismantled by soaking in cold water, and the bricks may be tremendous risks they face. used over and over again. without deterioration.Nothing ROUND THE WORLD IN INDUSTRY istheperfect like BRICKPLAYER has ever been produced before.It is the Christmas Gift for all who ideal hobby and will give hours of pleasure.It's only a week have a spirit of high adven- orso toChristmas, sc ture in their make-up. havea wordnowwith Mother and Father about vAth. Read how wrecks are lifted off the ocean bottom like diabolo 8 col lete ceToe BRICKPLAYER. reels. cs Wicl("j1/4bv.t:. v4.001\ Read of the methods of drilling for oil, the costs, and the drama ccro`Ne'aio",11/491- 61- ar'd SP"' behind the work. vis et shee's3Per1(3° Pgood -e d loYbricks1 SW°\ c),s: Read about the joke that sent a young Man prospecting for sitebr gold where none existed-only for him to make an amazing " strike."

Ask your bookseller to To the Publisher, GEORGE NEWNES, Ltd. get you ROUND THE (BookDept.), Tower House, Southampton WORLD ININDUS- Street, Strand, W.C.2. TRY, thus saving pos- Please send me by return ROUNDTHEWORLD tage. Alternatively, THE BRICK IN INDUSTRY. I enclose Postal Ordervalue 5 /6 sendtheform to the Publishers, with Pos- AND MORTAR No tal Order (pluspos- tage),and thebook BUILDING KIT will be sent direct to Name you. Address J. W. SPEAR & SONS, Ltd. ENFIELD, MIDDLESEX. Trade Inquiries Invited.

P.M. 12/39 134 NEWNES PRACTICAL MECHANICS December, 1939 WORKSHOP Behind the Scenes ina Modern Machine Shop. How the Milling, Shaping, Broaching, Grinding, Multiple Drilling Types of Cutter usually commence with the milling of the Different forms of cutter are used tocylinder head and sump joint faces, the produce various surfaces and profiles on thecutters usually being of the face type, with casting or forging. The plain milling cutterinserted blades. Often the milling machine cuts a flat surface parallel to its axis, thehas a rotating work -table with two vertical wider cutters usually having helical teeth inspindle cutters, one of which takes a rough order to prevent chatter.Narrow plaincut, and the other a finishing cut, the table cutters are used for producing grooves,being rotated to bring the casting under splines, keyways, etc. Side cutters; as theireach cutter in turn. When the cylinder head name suggests, have the cutting teeth onjoint face and the sump face have been their side faces. Two are often arranged onaccurately machined, the casting can be an arbor a short distance apart in order topositioned for the various other machining mill both sides of the component simultane-operations,such asmillingthetiming ously, an example being a valve rocker,cover flanges, manifold joints and similar which is clamped to the work -table andpoints. The main bearing housings also call passed slowly between the rapidly rotatingfor accurate machining, end -mills and side cutters. cutters generally being used to face up the A face mill has the cutting teeth arrangedvarious surfaces. on its outer face, and is used for machining flat surfaces, such as cylinder heads, etc.Shaping Machines An end -mill cuts both along its length, and Apart from the milling machine, the at the end, and is used for machiningshaper is sometimes used, chiefly to produce squared shoulders, and for cutting slots andflat surfaces.Although there are many some keyways. different designs, the principle of the shaper is illustrated in an accompanying sketch. It will be seen that the surface of the metal Drilling oil -feed holes in a crankshaft isa tricky or casting is " planed " by the tool carried operation callingforhighlyaccuratedrilling at one end of a ram. The ram forces the tool machines. The operator feeds the drillsinto the slowly forward across the metal, with a crankshaft shown, by hand quick return at the end of the stroke. During the return stroke the table carrying IN the machine shop the rough castings os the vice in which the work is clamped is forgings from the foundry pass through moved sideways slightly so that the next a number ofsuccessiveoperations. cuttingstroketakesplaceon afresh eventually emerging as finished parts ready, section of the casting.The ram itself is after inspection and test, for the assembly moved by a rack-and-pinion gearing, or by line. The batteries of machines are so a crank driven from an eccentric.The arranged that the sequence of machining GRINDING planer or shaper, however, has not the wide operations on any given component follows WHEEL scope of a milling machine. a logical order. In many cases, each machine is driven by its own electric motor, eliminat- Broaching ing the overhead shafting and belting which A broaching tool has a number of applica- is so often a source of accidents, while the The arrangement of grinding wheel and control tions in a modern factory. At one time, for parts are carried from one machine to wheel with the work resting on the support, as used instance, the splines in gear wheels were cut another on overhead or bench -level con- in centreless grinding is here shown in a simplified separately.Now, however, they are pro- veyors. form duced simultaneously by means of a broach, Universal Milling Machine which takes the form of a long, tapered bar, Milling the Cylinder Block providedwithsharpcuttingedgesin One of the most important items in the As a practical example of the use ofparallel rows. The narrow end of the broach modern machine shopistheuniversalmilling machines, operations on a cylinderis passed through the plain hole at the milling machine. Originally designed for theblock casting after it has been cleaned upcentre of the gear wheel, and the coupling of purpose of forming the spiral flutes in twiston leaving the foundry by shot blasting anda hydraulic or mechanically -operated ram drills, it is now adapted to a wide variety" pickling "for an hour -and -a -half in aattached toit. This pulls the broach of machining operations.Basically, theweak solution of sulphuric and hydrochloricthrough the gear, the cutting edges produc- milling machineconsistsof a rotatingacid, followed by immersion in a hot sodaing the splines. The final length of the bar spindle or arbor on which a cutter providedsolution to neutralise any remaining acid,is parallel. and is often provided with finer with a number of hardened cutting edges or teeth is carried.The arbor may be hori- TOOL HOLDER zontal or vertical, while below the cutter is an adjustable table to hold the work, so that the parts being machined can be fed up against thecutter, moved crosswiseor lengthwise in relation to it, or rotated at the FIXED JAW same time. When a number of machining OF VICE operations have to be performed on one part, a rotating table, located by a series of stops, known as an index head, is mounted on the work -table.Thus, when milling a "/All bolt with a hexagonal head, one cut might be made, the index head rotated through UMW one -sixth of a revolution, and a fresh cut taken, further revolutions of the index head being made until all the faces of the hexagon have been milled. This process is known as rapid indexing, and is capable of elaboration to provide almost any sequence of machin- The shaper is used for " planing" metal from castings, the tool, shown above (left) being ing operations. forced across the surface of the metal by means of the ram December, 1939 NEWNES PRACTICAL MECHANICS 135 THE FIRST ARTICLE PRACTICE OF A NEW SERIES Processes suchas CASING ENCLOSING ARBOR WITH various ELECTRIC MOTOR SPACING COLLARS and Turning are Carried Out WORK TABLE teeth, so that a good finishis obtained. Apart from forming splines, broaches are used to produce plain bores in gear wheels VERTICAL FEED and bearings, and for machining such parts as connecting rods. In the case of split big - CROSS FEED end bearings, each half may be separately broached by a D -shaped tool.Sometimes / the broach is passed through the bearing before it is split to form the two halves. Broacheswithflatorspecially -shaped cutting surfaces are also used in some cases PLAIN for external finishing of connecting rods and LONG other components. In this case the cutting GUTTERS teeth are arranged vertically behind the FEED work -table, and the work is fed up against SIDE CUTTERS them. Lathe Work The rough castings or forgings of a large number of parts, such as pistons, crank- shafts,etc.,andsimilarcircularcom- ponents are usually brought to the finished shape by turning in a lathe. This is similar END MILL in essentials to the ordinary workshop lathe, the chief difference being the very wide Theuppersketch shows the construction of one type of universal mil ing machine.Specialised rangeofattachmentsprovided,while out various machining operations in modern works, but the principle is control is largely automatic. It is usual for a designs are used tocarry number of operations to be carried out similar.Different types of cutter are also shown simultaneously. The rough turning and finish -turning on a layshaft gear cluster,and long -wearing surface. Similarly, on softMultiple Drilling for instance, may be carried out on anmetals, such as aluminium, only diamond After machining or turning operations, automatic lathe on which as many as sevenboring is usually theoilways and stud holes have to be drilled in tools are carried by the front slide, in orderdegree of accuracy requiredin moderna number of components. Multiple drilling to produce the correct diameter at variousengines in the case of machining operationsmachines are used in most cases, as many points along the shaft, while shoulders andon pistons, diamond turning being usedholes as possible being drilled at one opera- radii are simultaneously produced by fivewhen finishing the gudgeon pin bores andtion.At the Ford works, for instance, a tools on the rear slide. During the finishingfinish -turning the outside diameter. machine controlled by one man drills 92 operation an additional slide may be added, holes in the " V-8 " cylinder block casting operating from below, and carrying tools toTurning Crankshafts in 35 seconds. On Austin engines a multi - chamfer the edges of the gear collars. When Crankshafts are usually turned in lathesspindle tool simultaneously drills 53 holes in dealing with back axlecasings,specialof very heavy structure designed solely forboth ends, one side and the top of the designs of lathe enable both ends of the axlethis work. The various journals and flangesengine casting, the drills advancing from housing to be machined simultaneously.are machined in turn, elaborate precautionsfour sides, and withdrawing automatically Twenty or more tools may be iriuse at once. being taken ty ensure that the shaft iswhen the end of their feed is reached. Very A diamond -tipped tool is frequently usedcorrectly centred, and that whip or distor-similar is the threading operation, in which in the lathe when an exceptionally accuratetion is avoided.Similarly, the rough cam-the taps, after having cut the thread in finish is required.When turning out theshaft forgings are turned on special latheseach hole, reverse their motion and screw white metalled bore of a big -end bearing,on which the cutters for each cam arethemselves out. for instance,ithas been found that acontrolled bymastercams, to form the A tricky job is the drilling of crankshaft diamond produces a particularly smoothcorrect cam profiles on the shaft. oilways.The crankshaft is mounted in a

41111111111 Aspecial foam of lathe used for turning both ends of a rear -axle casing 4 face mill being used to machine the flanges on a cylinder block. The simultaneously. No fewer than twenty-one tools are in use at once during cutter can be clearlu seen on the left this operation 136 NEWNES PRACTICAL MECHANICS Dec ember, 1939 ing the grinding wheel, support and control wheel in relation to one another, a part canbeaccuratelyfinishedtowithin .0001 in. Parts such as gudgeon pins can be fed from a hopper, passed automatically across the face of the grinding wheel, and accurately finished at the rate of 100 or more pins an hour. By altering the shape of the grinding and Multiple drilling control wheels, moreover, tapered work or machines drilling several different diameters on one shaft can and reamering holes be produced with great accuracy. in cylinder blocks at It will be appreciated that throughout the Ford works the machine shop each cutting tool must be fed with a supply of special coolant ; this is a liquid which combines lubricating with cooling properties, and is fed onto the work from pipes adjace4t to the points at which cutting is taking place.Although most of the coolant iscaught and returned for reconditioning, some of it remains in the metal turnings and cuttings.Before these fixture, either horizontally or vertically, andalong each spline, the shaft being rotated toare loaded into trucks or compressed into long,slenderdrills,each driven by anbring another spline upwards when one issmall bricks in order to be returned with independent overhead electric motor, arefinished.Where gear teeth are concerned,other scrap metal to the furnaces, the fed into the webs by rotating a hand wheel.the grinding wheel is specially shaped incuttingoilisreclaimed by centrifugal The operator skilfully feeds the drill forwardorder to provide the correct tooth form. separators. No leis than 14 gallons of oil and then withdraws it, repeating the action Internal bores of gear wheels and similaris reclaimed from about 14 cwt. of " swarf." until the passages are complete. components which mustbeaccuratelyFour thousand gallons of oil are reclaimed finished, perhaps to take a ball race, areweekly. High -Speed Valve Grinding ground with the aid of a small grinding Frequently .drilling and reamering are carried out by one machine.In a typical instance the cylinder head of a six -cylinder NEWNES COMPREHENSIVE overhead-valve engine is clamped to a work WAR ATLAS table beneath a 24 -spindle drilling machine. you know where Emden is?Do The table has two positions. When in the D° forward position, the 12 valve -guide holes LAYSHAFT you know how many flying miles from are drilled simultaneously.The tableis GEAR Wilhelmshaven to Scapa Flow ?Do you then slid to the rear, when 12 reamers pass CLUSTER realise the depth of the Siegfried zone ? Do through the valve guide holes, enlarging you really know how much easier it is to them to just the right diameter to ensure follow the daily war news with the aid of a press fit for the guides. a really good map ? NEWNES COMPRE- To digress for a moment, it is interesting PLAIN HENSIVE WAR ATLAS which has just to note that even valve grinding is carried CLAMP been published at the modest price of ls. 6d. out automatically in a modern factory. BROACH is the finest atlas of its kind.It is abso- The valves are assembled in the guides, lutely up to date and gives eight pages of treated with abrasive compound, and lapped maps covering all the countries affected by in by.machines which give them a reciprocat- the present conflict and those bordering ing movement of over 100) strokes a minute, upon them. There is a special double page the valve being automatically lifted after CU TTING map of the Western Front showing the every eight strokes.As a result, the com- EDGES Siegfried and Maginot Zones and a number plete set of valves is perfectly ground in in of statistical facts relating to the compara- less than two minutes. tive strengths of the Naval, Military and Whenever machined parts have been Air Arms of thebelligerentcountries. case-hardened,finalfinishingmustbe BROACHED Particularly interesting is a chart showing carried out by grinding with an abrasive SPLINES thedistancesbyairbetweenvarious wheel, or by lapping with abrasive com- strategical points in Europe. pounds, as normal machine tools make no Two forms of broaches, one, for broaching plain bores, Thesemapsare,withoutadoubt, impression on the case-hardened surface. and the other for cutting splines absolutely ideal for the, home.No wall The part is machined to very nearly its finalwheel running at high speed on the end of aspace is required and they can be referred size before hardening, but some allowancespindle which can be passed into the bore.to instantly and in comfort while reading must be made for the slight distortion whichAt the Morris works the gear bores arethe paper for the print is large and clear usually takes place during carburising, re- and the atlas is the handy size of 12 in. finish -ground in this manner, the grindingby 94 in. heating and quenching. Where aflatwheel spindle rotating at over 12,000 r.p.m., surface is concerned, the final finishing iswhile the gear itself is being rotated at NEWNES COMPREHENSIVE WAR carried out by passing the component under450 r.p.m. ATLAS is obtainable through all bookstalls a rapidly rotating grinding wheel. The and newsagents or by post ls. 9d. from the The flanges and journals of crankshaftsPublishers,Tower House, Southampton wheelisautomatically trued up by aare usually finish -ground by mounting theStreet. Strand, London, W.C.2. diamond -tipped toolbeforeeachcutiscrankshaft in a special machine so that the taken. journalisrotated at high speed while This procedure is often followed in thethe grinding wheel is passed along it. Cam- case of the top and bottom faces of detach-shafts are ground after hardening in yet CHANGE OF PREMISES able cylinder blocks, and the top faces ofanother special grinding machine in which normal cylinder block and crankcase cast-the cut is controlled with extreme accuracy CHAMBERS COLLEGE and the ings; although these are not case-hardened,by moving the shaft towards and away NationalInstituteofEngineering the grinding enables a very accurate surfacefrom the grinding wheel, so that the correcthave removed their preinises to Chislehurst, to be obtained, essential in this case tocam profile is obtained. Kent,wheretheywillcontinuetheir prevent gasket leakage. In many cases the tutorial activities throughout the present cylinder blocks travel under the grindingGrinding Small Parts emergency. The whole of the tutorial and wheel while held in the magnetic bed of the Short circular parts are ground inaexecutive staff have now removed to this surface grinder. centre -less grinding machine.Instead ofaddress. mounting thepart between centres,it Grinding Splines is passed across the face of the grinding When splines have to be ground on awheel, and at the same time guided by a The first article of a series describing shaft after hardening, flab shaft is mountedrotating control wheel ; the part meanwhilethe construction of a 24 in. gauge Flying between the centres of a spline -grindingrests on a fixed support, as shown in anScotsman will appear in next month's machine, and the grinding wheel passedaccompanying sketch. By suitably position-issue. December, 1939 NEWNES PRACTICAL MECHANICS 137 A MODEL COTSWOLD VILLAGE By W. J. Bassett-Lowke M.I.Loco.E. A Representation in Miniature of the Village of Bourton- on-the-Water

of Bourton-on-the-Water itself,and has been built by Mr. Morris, landlord of the " Old New Inn " at Bourton since he took over three years ago. On my first visit to the village recently, A general view of the model village at Bourton-on-the-Water I had a talk to the chief mason, Mr. L. J. Cooke, and learnt from him some interesting WE are proud of our picturesqueowner visits his West Indian sugar plan-details of its construction. little villages, and, in the Cots-tation on St. Kitts. Approximately half an acre of real Cots- wolds, the very heart of England,Interesting Details wold stone has been used and they are still we find a cluster of beauty spots-Broad- But to return to the Bourton village, thisbuilding.Mr. Morris used to fetch the way,Burford,Stow-on-the-Wold,andhas the new feature of being a represen-stone in a trailer behind his car, and though Bourton-on-the-Water. tation in miniature of a real village-thatsince it was commenced eight or nine local The last-named has always been a pretty village, with itsgolden Cotswold stone houses and the river Windrush running through their midst, but in the last .two, -or three years it has acquired another interest. that of a " Xodel Village." To -day, we must admit, a model village isby no means unique. Most model enthusiasts havevisitedthe Bekonseot Model Village at Beaconsfield,complete with its working railway and ships.In the Cotswolds, too, quite near at hand, is the model seventeenth century fishing village of Mr. Charles P. Wade of Snowshill Manor. near Broadway, quite the finest and most accurately constructed of any I have seen. This village is made of perishable material and each winter is stowed away, when its

A Cotswold bungalow withwallsbuilt" in courses" and a garden wall built in the Cotswold manner, without cement men have been engaged on it, there were three men chiefly responsible for its being, Mr. Cooke, Mr. R. Pratley, his assistant mason, and Mr. H. Hagg who helps with the excavating and does the gardening work of the model village. Miniature Mountain Glen The scaleis1/9th actualsize,which equals 1 1/3 in. to the foot, and the idea of building it came to Mr. Morris when he decided to turn the kitchen garden behind the" Old New Inn " into a miniature Mountain Glen with hills, rivers and water- The church-one of the finest pieces of model work in the village falls.He made the bridges in Venetian 138 NEWNES PRACTICAL MECHANICS December, 1939 candlestick makers' shops-not to mention the Police Station-all with their names and signs and little front gardens exactly as they really are a few hundred yards away in Bourton itself.There is the chapel with itsfinerose -window, and thepiece de resistance is, I consider, the village church. The greater part of this is built " in courses " just as the real one (instead of being marked out in bricks on a solid slab of stone) and on the northern side the door swings open to reveal the inside with its nave filled with pews with prayer books and hassocks. As I gazed there came to my ears in clear treble tones, the hymn " Hear My Prayer."Just behind the church was a pretty cottage building made completely " in courses," with a realistic Cotswold stone wall built up without mortar. A fine piece of model work. Model of a Model At the entrance to the village is the model of " The Old New Inn "itself with its sign, its sundial, its saddlestones,and behind it-a model of the model !Another tiny river-three inches wide this time The old Mill with working water mill insteadofthreefeet-ManorHouse, style as those in Bourton village and from thence developed the idea of a model Bourton-on-the-Water. The first building, Mr. Cooke tells me, was the memorial which sprang up among the raspberry canes !Then came the mill with its wheel over which the little Windrush starts its flow.Outside the mill is the Jolly Miller, who stands arms akimbo, with millstones around his feet-and a happy smile on his face-albeit of stone !The rockery waterfall has given the gardener wonderful scope for his talent, and the water I discovered was pumped from a well in the garden itself at just the right pressure to give the normal flow and to turn the mill wheel. The village itself was mapped out from an old council plan and Mr. Morris has had the whole -hearted help of thevillagers with details, such as the reproduction of gardens,theshopfrontsand window dressing, and the vital question of measure- ments. The Village Church Settingoff down one of the streets, treading carefully as Gulliver did in Lilliput, you come across butchers', bakers' and The mason's workshop, situated close by the village

Church, Mill and Inn-the stream flowing, the mill wheel turning, the water cascading down the rockery. A model in fact nine times as small again. At the top of the village I had a look in thespecialperiscope whichbrings the village up to the level of the eye, and makes it appear to be as in life. House Interiors All the lamps and the house interiors light up after dark, and the music trans- mission for the church is by radio gramo- phone.Each year as the stone weathers, it will become more and more like the real village, but of course there is still much work to be done, for new buildings are continually requested.The churchfor instance actually is well out of the village on an old Saxon site, but was incorporated by general vote, in the model. Before I left I had a peep in the stone shop and show here a picture of the stone laid out in slabs.The entrance fee of sixpence charged for visiting the village goes entirely towards the continual work entailed in upkeep and new building-a A model of the model situated at the back of the model of The Old New Inn" charge which all model lovers will appreciate. December, 1939 NEWNES PRACTICAL MECHANICS 139 Radio Control of Model Aeroplanes By E. L. Rockwood Webb (Concluded from page 54 of last month's issue)

of the little petrol engine makes it necessary to do this to shock -mount the receiver. otherwise the relay contacts world vibrate back and forth independent of the signal. The Sigma relay is shown in the bottom view directly in front of the panel mounting the Fahnestock clips which serve to lead connections from the unit.The plate by- pass condenser is standing on end in front of it,directly behind the APC-25 tuning condenser.To the right of the latter is a high -frequency honeycomb choke used in the plate circuit. Adjustment of the Detector Various values of grid leak and condenser Fig. I0.-The 5 -ft. biplane model which is equipped with radio control. The tuning other than those shown in the diagram meter whichisremoved for flyingcan beseen just above the landing gear furnished with the tube may be used, as well as other values of plate by-pass condenser. THE whole thing may be replaced bybottom view.The balsa -wood case to theOperation of the set should be such as to a small motor operating on 6 voltsright is a dust -cover for the receiver. Thecause an audio -frequency tone to be audible and usingaform of commutatortube has been unbased for lightness, thewhen the ear is placed near the coil of the chopper. The vibrator systern is the easiestweight of the base and socket necessaryrelay. Detection of this tone may be accom- arrangement to make, however. being about 2 oz. A strap of stiff cardboardplished by inserting a pair of 'phones into is bolted around the tube and down onthe platecircuit. But thisalters the Drive System Details eitherside,tothe balsa panel of theresistance in the plate circuit, changing the The steering unit drive starts with areceiver, to hold the tube in place. tone and the value of plate current so that worm gear on the motor shaft. This drives The photographs show the useof awhen the 'phones are removed the condi- a short jack -shaft with a 16 -tooth pinionblock of synthetic sponge taken from ations are changed.The grid leak and on one end ; a worm gear on the other endbath sponge and glued to the receiver panelcondenser values will have a great effect on drives a 32 -tooth gear on a second jackand to the piece of balsa which shows onwhat tones may be obtained, but the actual shaft at right angles to the first, and the disctop of it in the bottom view.The set isadjustment depends on the aerial coupling. is mounted on the far end of the secondmounted in the 'plane by resting the unit Grid -leakand- condenservaluesalso jack shaft. A pin near the edge of the disc.on cross -pieces built into the model andaffect the peak value of plate current which operates in the slot of the scotch yoke. Thelashing withrubber bands the narrowis available to pull up the relay when no jack shafts are3/32 -in. model -aeroplaneproject ions to the crosspieces. The vibrationsignal is being received.The more current landing -gear wire or piano wire-the bear- through the relay, the less chance there is ings are 3/16 -in.outside diameter brass of vibration affecting the contacts, and the tubing glued down to the balsa frame of the spring may also be set up tighter. However, unit. A small quantity of vaseline is used operatingconditionsproducing11ma. as lubricant.Machine screws used in the correspond to a condition of low sensitivity unit are No. 2-56.The gears may be to signals. obtained, with the motor, at a model rail- Very low frequency audio tones also way supply store.The completed steering reduce sensitivity and both low tones and unit used by the writer weighed 31 oz.. high plate current introduce a lag in the including the left -turn shut-off switch. response of the relay.I have found a The receiver finally decided upon and in satisfactory arrangement- tobe that of use at the present time (diagram Fig. 7) allowing a current of about I ma., adjusting is a simpler device than that shown in Fig. the spring of the relay to allow the armature 4 and diagrammed in Fig. 1.The RK62 to pull up smartly at that value, and using developed in the last few years by the a very high audio tone obtained by adjust- Raytheon Company is a special valve for ment of antenna coupling. Cushioning the the one purpose of operating a relay directly receiver and relay with the synthetic sponge in its plate circuit by introducing a radio material gives satisfactory freedom from frequency signal into its grid. The valve is vibration effects. a thyratron-it behaves as a normal detec- In this connection the writer rigged up a. tor unless the bias falls below a certain vibration tester, using a weight attached off definite amount.Then suddenly the gas centre on a block of wood fastened to the content in the tube ionizes, greatly reducing shaft of a series soda -mixer electric motor. the internal resistance of the valve, causing The receiver in its shock -absorbing mount more current to flow and operating the and the motor were then mounted upon a relay. When the valve operates as an board which was then mounted on rubber oscillating detector, the bias is high enough so it was free to vibrate. A variable series to limit the plate current to a value of resistance controlled the motor speed and about .02 ma.If itis caused to super - consequently the degree of vibration. The regenerate, the current may be 1.5 ma. or receiver was operated and a signal sent into so. A signal introduced into the grid circuit it, then the vibration was increased until the will restore the bias, dropping the current Figs.8and 9.-(Top)Topview ofRK62receiver point was found where the set was no to the lower value. showingbalsacover fortheunit. (Below) longer reliable in its operation due to relay Fig. 8 shows the top view of the receiver Underneath view of RK62 receiver showing the chatter.This point was found, with the using this tube,andFig.9 shows the relay and shock -absorbing pads of sponge rubber arrangement shown, to be vibration of a 140 NEWNES PRACTICAL MECHANICS December, 1939 degreemuch moreviolentthanthat The best method of engaging in thethe flipper cuts down the air and a trigger encountered in actual use in the airplane.fascinating sport of radio -controlled modellocks the flipper in place. From then on the aeroplanes is to co-operate with someonerudder may be used normally to steer the Plane Aerials who has already had some experience with'plane as it glides in for a landing. A quick In Fig. 10 is shown a 5 -ft. span biplane" petrol jobs," as they are called. He willfull right rudder causes the yoke to operate model of the U.S. Army Ferliner-Joyceprobably know the vagaries of the species,a trip which releases the flip trigger. This pursuit plane of several years- ago.Thewhich are numerous enough to bewilderhas a spring causing it to jump back, open- aerial used on this installation was aboutthe novice who is more versed only in theing the air intake fully. The model may 10 ft. long, starting from the lead-in locatedradio end ,of the game. This practice willthen be steered normally under power as in the fuselage opposite the leading edgessave the anguish of cracking up a modellong as the position of extreme left rudder of the wings, going to the tip of the rudderwhich required many hours of carefulis avoided. fin, from there to the right wing tip, andconstruction, to say nothing of probable The thrills of flying these small 'planes then to the left wing tip. A small spring wasdamage to delicate radio equipment. Onseem to appeal to anyone who has ever used at the first fitting to maintain tensionthe other hand he will be delighted with theseen them in action. Their normal rather without drawing the wires too tight. Thisuse of a control which will prevent theshort life may be prolonged many times by length of aerial is not entirely necessary,eventual loss of nearly every " free flying "flying them under control, and the sport° but it increased the sensitivity greatly. model. These losses arc inevitable no mattercan be increased greatly by the ability to In other installations, such as a 6 -ft. spanhow good the design and adjustment due tomake them perform exactly according to model of a Curtis Robin monoplane anuncontrollable collisions with " immovablethe owner's wishes. aerial of only 30 in. was used from the frontobjects" such as buildings and electric poles, of the cabin to the rudder tip. The aerialto say nothing of the damage done by "cross-Control Frequency may be enclosed in the fuselage if desired,wind " and " down -wind " landings which While 56 Mc., is the frequency commonly or the wings may be fitted with an aerialare not preventable without remote control.employed in thesecontrols,112. Mc. is before they are covered. The writs, is in the fortunate positionequally satisfactory for the purpose. This Resonating Receiver and Transmitter of having had several years' experience withcuts down the size of the portable aerial " free -flying " models before adding controlused in the transmitter and the valves In Fig. 10 will be noted a meter justto them, as well as having actively engagedmentioned in the two receivers of this above the landing gear of the model. This article perform very well at this frequency. isthe plate milliammeter shown in thein short-wave radio since 1918. circuit in Fig. 7, and has been converted Many systems of operating the desiredEquipment should be designed from the from an old 0-5 pin -jack voltmeter.It iscontrol surfaces of the model will occur tostandpoint of low weight as well as electrical made removable by plugging it into a pairtheinterested amateurif hehas anyefficiency.Also, the construction methods of pin -jacks in the fuselage. To adjust themechanical ability whatever. The engineemployed in model aeroplane building will transmitter to the receiver, the latter inspeed has been changed from idling to full,somewhat modify the tendencies that are position in the 'plane is removed to aboutand back to idling, by the writer, using thenatural in a constructor who has been fifty feet from the oscillator unit on theequipment above described. The air intakedealing exclusively in equipment designed tripod, and set on the ground. The fre-of the petrol engine is simply fitted with afrom the angle of the radio experimenter. quency of the transmitter is adjusted tillflipper which cuts down the air flowingFor this reason, it is again urged that co- maximum plate current dip shown in thisinto the mixing valve.Thisflipperisoperation with a builder of model aero- meter is obtained. controlled by a piano -wire lever which isplanes will greatly increase the chances of The degree of this dip is led back to the scotch yoke of the steeringending up with asuccessfulradio -con- what by adjustment of R Fig. 7, the shaftunit. When the model is ruddered full lefttrolled model aeroplane. of which may be seen to the right and above the meter in the fuselage of the 'plane. This gation developed, how and why ships sail, is adjusted to compensate somewhat for and how to recognise the different types of changes in H.T. battery voltage as the .;-130010 troth ships afloat. The book is printed in bold batteryages. Its adjustment must be made after resonance has been reached type, and is in simple language which any between receiver and transmitter. When intelligent child can understand. these adjustments have been made the `How TheyFly." By JamesGardner. meter is removed and its place taken by a Published by Country Life, Ltd. 32 pages. link of No. 14 wire or a short length of Price 3s. 6d. hookup wire with a 'phone tip soldered to THIS is a very interesting book, especially ,each end. " The Elements of Sheet -Metal Work." By for young readers, and explains with W. Cookson and A. Bold.Published bythe aid of many coloured illustrations, and What Surfaces To Control ? The Technical Press,Ltd.120 pages.diagrams, the flying mechanism of insects, Regardingthedecisionastowhat Price 6s. net. birds and aeroplanes. A brief description of controls are desirable in a model aeroplane, ALL interested in pattern development,the work of early pioneers of aeronautics, it may be mentioned here that the first includingapprentices,draughtsmenis followed by some interesting facts con- thing many people with a smattering ofand students, will find much useful informa-cerning modern aeroplanes, and how they aeronautical knowledge willthink of istion in this book, which clearly explainsare piloted.The book concludes with a aileron control.This is possibly the leastsome of the elementary problems connectedpeep into the future. useful of all the controls possible. Dihedralwith sheet metal work. The authors have built into the wings, that is, the angle of theavoided technical details, and have striven" The Old English Master Clockmakers." wing panel to each other and to the hori-to make the information as practical as By HerbertCescinsky. Publishedby zontal, takes the place of thiscontrol,possible.The explanations accompanying George Routledge and Sons, Ltd. 182 making the'planeautomatically bankcertain problems have been put in easily pages, 227 illustrations.Price 15s. Od. when it is steered into a turn, and main-understandable form. The book is divided net. taining the model on an even keel laterallyinto eleven chapters, covering such subjects THIS book is intended as a guide for the in flight. A model 'plane does not have toas Workshop Arithmetic; Geometry and clock collector, antiquarian, and antique be " flown " or continually controlled toMensuration;PatternLayout;Parallel - dealer.It has been written by an acknow- keep it in the air, but due to inherentLine Development ;Radial -Line Develop.ledged expert on the subject, and is pro- stabilitywillflyitself and needs onlyment ;Triangulation ;Metals and Theirfusely illustrated with fine examples of to be directed. Even the dreaded " stall "Properties ;andWorkshopToolsandEnglish clocks from private sources.The or loss of lift due to too steep a climb, willAppliances. The book is illustrated withbookdescribestheproblemsofearly automatically be rectified if the model isnumerous diagrams, and also includes anhorology, and deals with the development properly built. A tail -spin is a very rareindex. of the pendulum, trains and escapements. occurrence in a model, and will never occur Brass lantern clocks, clock dials, and the if the model has been properly built. " Ships: How they Sail." By James Holland.development of grandfather clock cases are Rudder control alone may be used to Published by Country Life, Ltd. 24 pages.discussed in following chapters, illustrated cause the 'plane to climb, lose altitude, head Price 3s. 6d. by some fine examples by old masters such into the wind and return to the landing area.THE story of the sailing ship and steam-asFromanteel, Edward East,William A right turn normally causes a model to boat makes interesting reading at theClement, Thomas Tompion, Henry Jones, lose altitude in a spiral turn whereas a leftpresent time, especially when presented inDaniel Quare, and George Graham. Various turn causes a climbing spiral due to thethe attractive style displayed in this book.types of clock cases are illustrated, including influence of the gyroscopic action of theIntended for the younger generation, thesome designs by Chippendale and Sheraton, motor swinging a propeller at upward ofbook explains, with the aid of numerousand there is also a chapter on Mantel or 5,000 r. p.m . beautifully coloured illustrations, how navi-Table Clocks. December, 1939 NEWNES PRACTICAL MECHANICS 141 is actually sealed.The reason for this is that until the official search has been made on a Patent Application, which isonly made after the filing of a Complete Specifi- QUERIES cation, neither the inventor nor the firm proposing to take an interest in the inven- tion. knows the extent of the novelty, or the extent of the monopoly which willbe ENQUIRIES obtainable by the patent. If the firm is entitled to the first refusal of a sole licence, the sum to he paid for the A stampedaddressederweiope,.hreepenny option should be more than if for a general stamps, and the query coupon from the current issue, which appears on page iii of cover, must be licence. The sum to be paid for any option enclosed with every letter containing a query. must depend on the importance of the Every query and drawing which is sent must bear invention and the particular trade con- the name and address of the sender. Send your Striking An Arc queries to the Editor, PRACTICAL MECHANICS. cerned, but in any case it is a matter of Geo. Newnes, Ltd., Tower House, Southampton agreement between the parties, and should USING twocarbonstakenfromthe Street, Strand, London. W.C.2. bear some relation to the amount to be centre of dry cells,I endeavoured to paid as royalty during the first year of strike an arc. The supply was 200 v. A.C., manufacture. and the maximum current available wasTwinob "switch.The switchhas two 3 amps. The arc obtained was fairly strong,arms, one of which is spring controlled andImprovedElectricLightBulb but would remain steady for a few secondsreturns itself to the open position when the only, and then require re -striking. knob is released. Socket - Was the supply wrong, or was the carbon HAVE thought of an idea for improving unsuitable? How can I make the experimentA Football Game Ian electric light bulb socket, and would successful ?-M. P. (Surrey). like your opinion astoitsnovelty and I HAVE constructedafootballgamewhether it forms fit subject matter for a WHEN attempting to work a small arc I(drawing attached), and would like your light from a 200 volt A.C. circuit it isopinion as to novelty, etc., also if suitablepatent.-E. S. (Liverpool). necessarytohaveastabilisingseriesfor patent protection.The playing surface THE improved electric light bulb socket, resistance in circuit.There is a counteris formed by the wood laths in this case, if novel, forms fitsubject for pro- EMF of 30-35 volts across the arc itself,but it could be produced in metal, clearancetection by letters patent. There may be a consequentlyabou%170volts must beslots for the strikers being punched out.-market for such an invention, but itis dissipated in the resistance.If the currentB. G. (South Wales). considered that theadditionalcostof is to be limited to 3 amperes therefore the THE improved football game, if novel,manufacture would militateagainstits value of the resistance will he about 57 forms fit subject matter for protectiongeneral adoption and so not prove com- ohms.The actual EMF across the arcby patent. The invention is thought to bemercially successful. It is also thought that will be found to vary with its length, so thatnovel, but as a considerable number ofthe drawbacks inherent in making and theresistanceshouldbevariablealso.patents have been granted for such games,maintaining the additional contacts would Drycellbattery carbons are not veryparticularlyautomaticor coinfreednullify the advantages to be gained by the suitable for the experiment, nor do youmachinesfor.playing games,you aremore complicated construction. state what diameter you are using. Prob-advised to search amongst prior patent ably you will not get a steady arc withspecificationsdealingwith the subject,Vitreous Enamelling any carbons larger than 7 or 8 millimetresbefore expending money in protecting theI AM interested in the commercial appli- in diameter. A suitable grade can be ob-invention. cation of vitreous enamelling. tained from The General Electric Co., Ltd., I wish to enamel some small refrigerator Magnet House, Kingsway, London, W.C.2.Option on an Invention cabinets (approx. 3 ft. sq.). Is it necessary to shot -blast steel to obtain Connections of Single -Phase I HOLD a provisional patent in which a particular firm is interested. They wanta good bond ?If so, where can I obtain Induction Motor me togrant them a3 -months'option,chilled iron shot and what is price per cwt. I HAVE unfortunately burnt out my a h.p.afterthe granting of the patent proper,of shot ? single-phase induction motor, 250 A.C. atduring which time they would have the Is it necessary to pickle steel ?If so can first refusal of a licence. They are willingyou recommend a good pickling solution ? 50 cycles, 21 kilowatt running at 1450 r.p.m. What isthe price per gallon of white Ihave rewound it but am in doubt asto pay me a small sum for this option. Can you give me some idea of what thisvitreousenamelandwherecanitbe to how the four connections are connected obtained ? to the supply via the starter switch.Forsum should be ? The invention,ifitprovessuccessful, What is the fusing temperature of the your information there are four large coils enamel? Can it be fired on and the article with smallercoilsinside,the smallcoil would be of major importance.-W. W. (Somerset). removed from the oven, or isit better to being wound in the same direction as its leave article to slowly cool ? accompanyinglargecoil;eachofthe AS you have not given any particulars Can you advise me of price and where I eight coils having 90 turns of 22 SWG wire. of your invention for which you havecan obtain any up-to-date literature on the --G. B. (Hinckley). obtained provisional protection (not pro-subject ?-O. I. (New Zealand). YOUR diagrams accompanying the en-visional patent as stated by you), itis I T isnot ordinarily necessary to shot- or quiry show four sets of running coils,almost impossible to give you the informa- sand -blast steel or other metal previous eachconsistingof two concentricsetstion you desire. to vitreous enamelling it.Indeed, such forming onepole. Thesecoilsrequire Itisquite a usual proceeding for antreatment might very easily he injurious connecting all in series so that the circula-inventor to give a firm likely to be interestedowing toitsliabilityto give a highly tionof currentalternatesfirstinoneinhis invention an option for a limitedroughened surface to the metal. direction and then the other in consecutiveperiod, either after the complete specifica- Usually, iron sheets which are to be pole groups.This would he accomplishedtion has been accepted or after a patentenamelled are placed in special furnaces and if you connect your second and third leads heated to a dull red heat.This treatment together.Nothing is shown, however, in loosens the surface scale, which is then your sketch as to the starting coils, which PRACTICAL MECHANICS dissolved off by immersing the sheet metal arealwaysnecessaryfOrstartingup in a pickling bath comprising dilute hydro- single-phase motors. These should consist HANDBOOK chloric or sulphuric acid.The sheets are of another four sets of coils of finer gauge scrubbed beneath the surface of .he acid in wire, arranged with their pole centres half By F. J. CAMM. order to remove the scale quickly, after way between those of the main running An extremely valuable book, packed withfacts which they are transferred to fresh water coils. When starting up, these two sets of and figures, tables and formulae for the mechanic, and thoroughly well washed.Sometimes, coils, main and starting, must be put in engineer and designer. duringthislatteirwashing process,the paralleluntil the motor acquires nearly sheets are scrubbed with perfectly clean full speed, the- starting coils _ then being From all booksellers 6s. net, by poet 6.. 3d. from sand made into a paste with water. A final cut out, leaving the running coils only in the publisher: George Newnes, Ltd. (Book Dept.`. washing with water follows. after which the circuit.This can best be carried out if hand - Tower House, Southampton Street, Strand, W.C.2. cleaned metalsurfaceisready forthe startingisresorted to by a" Lundberg application of any enamel. 142 NEWNES PRACTICAL MECHANICS December, 1939 It is the custom of many enamelling firmsfitsubjectforprotectionbyletters TOUR STUDENTS in England to make up their own suppliespatent. of enamel and each firm possesses formulae The invention appears to be a practicable which are more or less secret.You may,one, and if novel, should have commercial GET GOOD JOBS however, obtain supplies of ordinary whitevalue.You are advised to protect your invention before submitting it to persons You canqualifyforawell -paid vitreous enamel from the following firms :- technicalpost,or learn to earn National Enamels, Ltd., Norman Road,likely to be interested. The least expensive money in your spare time.Send East Greenwich, London, S.E.10. way of obtaining protection is to file an now fordetailsof our modern L. le Personne & Co., Ltd., 99 Cannonapplication for patent with a provisional Home -study Radio Courses Street, London, E.C.4. specification which will give you about 12 TheFerroEnamellingCompany ofmonths, during which time it should be Holland, Rotterdam, Holland. possible to ascertain if the invention is T. & C. RADIO COLLEGE Incandescent Heat Co., Ltd., Cornwalllikely to be commercially successful. 1/4FAIRFAX HOUSE, HIGH HOLBORN, W.C.I Road, Smethwick, Birmingham. Messrs. La Barre & Co., Heath Town.Copper Sulphide WANTED Works, Wolverhampton. COPPER sulphide, CuS, as made by the Used Trix and Bassett-Lowke Locos., rolling Messrs. John King & Son (Enamellers), direct combination of copper scrap and stock and track. Any quantity. Also models, Ltd., Whittington Moor, Chesterfield. sulphur heated in an open crucible,is a airguns, boats, meccano, etc.Turn your Thefusiontemperaturesof vitreous unwanted goods into cash.Send carriage brittle, even friable, substance.Itis not, forward. Best cash offer by return. Or call. enamels vary a good deal. Around achemically, very stable, tending to revert LOCAL AGENT FOR TRIX TWIN RAIL- thousanddegreesFahrenheit(whichisto Cu2S when heated and to become CuSO4 WAY. SALES AND SERVICE DEPOT. rather below the melting point of copper)when damped.It disintegrates into a red " MODELS, LATHES & TOOLS'' is an average temperature. After fusion ofhot powdery ash of unknown composition 399, Hendon Way, N.W.4 the enamel in a specially designed mufflewhen acting as a (fairly good) conductor Telephone: Hendon, 6642 furnace (a process which takes about 15to a direct current of say 12 volts x 2 amps. minutes) the metal sheet upon which theMoreover, making good electrical contact '`INDISPENSABLE IN YOUR' enamel has been allowed to fuse or " run "with it is not easy. may be withdrawn from the furnace and In Art. 938 of Ganot's Physics (Atkinson), Raz0 allowed to cool down at its own rate, i.e.a description is given of a thermo-electric without any special control. battery by Becquerel which employs solid The literature on the subject of vitreouspermanent blocks of this material approxi- enamelling is very scanty. The only bookmately 4 in. xin. x on the subject of which we are aware is the I should be grateful if you could give following :- any suggestions as to how copper sulphide L. R. Mernagh :" The Manufacture ofmight be made in such solid block form.- et, Enamelled Ware." (18s. nett.) This can be obtained through any British booksellerJ. J. (Hants.). \ .ts \-*!./' (as, for instance, Messrs. W. & G. Foyle, YOU cannot prevent the reduct ion of Having acquired complete Factory's output of this superior appliance Ltd., Charing Cross Road, London, W.C.2), cupric to cuprous sulphide by the action enables us to pass immense saving on to Public.Every home of heat, but its oxidation to copper sulphate A.R.P. refuge room needs one.Uses little more than 4 -unit. but even this does not cover the subject Size Bin. by Sin.Usual Our Price 6/6.Post & Packing 9d. fully. will not take place unless moistureis Flex and Plug VS extra. A definitely superior article --not to be confused with similar foreign goods being advertised. Satisfaction aspresent.Hence by preserving the dry guaranteed.Send P.O. 8/6. With complete confidenceto :- material in dry air, this process of oxidation PndM.), 1 Whitehall. previously indicated, find it advantageous WHITEHALLSUPPLIES(Dept.Loon,5S.W.1. not to publish the technical details of theircould be prevented,particularlyif the Calera invited Open all day Saturday W If I 6962 processes. Hence, it is next to impossible tosulphide were perfectly pure. ascertain detail practical information. ' The only way in which you can obtain No doubt, however, you may find somepure cupric sulphide, CuS, in block form of the firms whose addresses we have givenis by submitting the material to powerful, FREE SERVICEyou willing to assist you with specialisedhydraulic compression.Even then, how- information and to forward you any liter-ever, the material would still show friable ature which they may have available. Wepropertieswhichcould,ofcourse,be would not, however, advise you to embarklessened by incorporating a small proportion FOR READERSupon large-scale vitreous enamelling untilof an adhesive and binder with it. In order you are quite sure that you have a workableto obtain the sulphide in the pure condition, READERS requiringinformationprocess in your hands. itis best to precipitate copper sulphate concerning goods or services ad- with hydrogen sulphide. vertised in PRACTICAL MECHANICS Small cubes(orblocks) and rods of should give names of Advertisers fromPressure Indicator copper sulphide are articles of commerce whom particulars are desired.AnyI ENCLOSE details of an improved pressureand may be obtained from Messrs. Harring- number of names may be included and indicator for pneumatic tyres. What doton Bros., Ltd., City Road, London, E.C. we will obtain for you catalogues, lists,you think of its novelty, practicability andProbably, also, Messrs.Philip Harris & and any other information you may becommercial possibilities?-H. N. (Belfast). Co., Ltd., Laboratory suppliers,Birmingham, wanting. THERE IS NO CHARGETHEimproved pressure indicatorformay be able to supply the material in the FOR THIS SERVICE. pneumatic tyres is novel, and formsfairly large block -form which you require. Readers desiring particulars from a number of Advertisers will, by this method, save time and postage.If any Advertiser stipulates that stamps or postal orders are necessary before samples or catalogues are sent, please enclose the necessary The Handiest Book Yet Published for Draughtsmen, Fitters, Turners, amount with your instructions. You are cordially Mechanics,Pattern -Makers, Millwrightsand invited to make full use of this Service. Erectors,Foundrymen, Technical Students ADVERT. SERVICE DEPT*I WORKSHOP CALCULATIONS, TABLES AND FORMULA PRACTICAL MECHANICS, By F. J. CAMM (Editor of Practical Mechanics) TOWER HOUSE, SOUTHAMPTON 3/6 or 3/10 by post from Geo. Newnes, Ltd., Tower House, Southampton Street, Strand, STREET, STRAND, W.C.2 London, W.C.2. Its Comprehensive and Fully Illustrated Contents include:-The Micrometer and Vernier; Mensuration; Trigonometrical Formula; Extracting Square Root; Extracting Cube Root; Please obtain and send to me particulars Continued Fractions; Arithmetical Progression; Geometrical Progression; Harmonical fromtheAdvertisersin your December Progression; English Weights and Measures; Horse Power; Force, Energy and Power; Heat, Time, and Velocity; Electrical Units; Comparjson of Thermometers; Pulleys; Parallelogram issue whose names I give on the list attached. Forces; Pendulum; Levers; Centrifugal Force; Moments of Inertia; Metric Systems; Screw Cutting; Tool Grinding Angles; Lubricants for Cutting; Spur Gearing; Tapers and Angles; Advertiser I Page No. I Information Required Bevel Gears; Worm and Worm Wheels; Spiral or Screwgearing;Pulley Calculations; The Dividing Head; Differential Indexing; The Slide Rule; H.. Required to Drive Shop Tools; Table of Cutting Speeds; Proportion of Keys and Cotters; Standard Screw Threads; Drill Attach sheet of paper, with particulars, Sizes; Circle Spacing Table; Tapers and Angles; Melting Points of Metals; Weights of Materials; Twist Drills for Wood Screws; Wood Screw Proportions; Weights of Woods; and your name and address (written in Powers and Roots of Numbers; Wire and Sheet -Metal Gauges; Natural Sines, Cosines and BLOCKletters),withdate, tothis Tangents; Logarithms and Antilogarithms. announcement. December, 1939 NEWNES PRACTICAL MECHANICS 143 Photo -electric Cells

..IMPORTANT/.. I AM interestedintheconstructionof ELECTRADIX photo -electric cells. mA.otRo.rPs..25AN..D EXPERIMENTERS BARGAINS FORGET THE BLACK -OUT How couldI construct a" selenium " MOTORS. All sizes from 1 40 h.p., 15 -. h.p. D.C. cell, starting with selenium sticks ? MOTORS. MOTORS. MOTORS. Small and Medium. A and REMEMBER large stock of really fractional horse -power motors have CouldIconstruct a cellusing cuprous abenedn230rel,e_stolstesdat bargain prices. 8 volts, 50 volts, 100 volts oxide (powder), and copper ? A.C. MAINS MOTORS. Enclosed, self -start on load. A.C. repulsion. 1:60 h.p.. with pulley. type 36, 1,500 revs.. Have photo -electriccellsto be used in 18 6. Ditto. 1'16 h.p.. G.E.C., 3,500 revs., 27'6. Induction 1 10 h.p., 2,500 revs.. 35.-. h.p.. 1,425 revs., 491-. S-V/131121DIS conjunction with a battery, or do they alone D.C. MAINS MOTORS. 1-40 h.p., 110 v. or 220 v.. K.B. give sufficient current to enable a reading toseries, 1,750 revs.. 15 -.Ditto, 1 St h.p.. G.E,C., 230 v. AERONAUTICAL MODELS series. 2,000 revs., 16 -.Ditto, 1'12 h.p.. betaken withamilliammeter ?-B.V. Croydon 110 and 230 v. shunt, 30:-. ( Porthcawl). DIX - MIPANTA VEST POCKET TESTER.A versatile moving -iron FOR CHRISTMAS I T isnotan easy matter todescribe multi -range meter for service on A.C. or D.C. THREE ranges of volts: 0-7.5. Now isthe time to prepare a PRIZE- adequately the construction of a selenium 0-150,0-300. Used for MILLIAMPS, reads: 121 m.o. In black bake- WINNER for competition in the Seventh cell within the compass of a single reply. lite case. 2(in. x 2: In., with Annual Model Aeroplane However, you can make a simple type ofpair of test leads, and plugs.19/6 ELECTRADI X It ADIOS WONDER- selenium cell by winding twenty turns of FUL BARGAINS, Home Recording RALLY OF THE SKYBIRD 32's gauge bare copper wire around a flat with the all -geared FE GII Electric Recorder. Ball Bear- LEAGUE piece of unglazed porcelain, mica, slate or ingcentre gear box and soapstone. The wire turns should be close - traverse rod.Is the lowest Write -direct for particulars. , -.7- priced electric home recorder together but must not touch.Now, take a that will fit any gramo. The set.withTracking Gear. If normal shopping presents difficulties stick of selenium, heat it gently in a flame Mpg Pickup and tone you can obtain your SKYBIRD model by and rub it all over one side of the coil thus GM, arm with diamond, - 37/6 means of SKYBIRD GIFT CARDS made, much in the same way as you would 4.0 Gear only. 21 6. .WOUSTIC RECORDERS. Great Vun.Lasting In- which may be purchased 5/- each from rub sealing wax over a surfaCe.Aim at terest.Cost is low. New MIVOICE acoustic sets, com- agents, or from SKYBIRDS. With each getting a thin, even surface of selenium onplete outfits in carton de luxe. 16,-. No. 2 Mivoice, 10/6. Junior. 5 6. card there is an illustrated Price List from to the insulating surface and at getting the ELECTRIC SOLDERING IRONS.Heavy workshop type.125 watts, 220,2.50 volts, OIL which toorder any models required direct selenium well embedded between the wireBELLS. G.P.O. type trembler Circular Desk Bell. with from SKYBIRDS, (Service Dept. P.M.), turns. movement in gong, 143, Wall Bells, trembler. 2 6. Ditto, large size, 7 6. Large mfta112-volt single stroke Bells,10:- 3 Aldermanbury Avenue, London, E.C.2. The cell, thus prepared, requires " form- MAINS BELLS.A.R.P.220 -volt Ironclad Trembler ing."This is effected by very carefullyAlarm Bells, with 10-11. gong, outdoor type, listed, 80'-. Sale. 37t6. heating the selenium up toitsmeltingSingle Bell Wire, 1 - 101 yards. Twin Bell Wire. 3.- 100 yards. Hooters. 6 and 12 volts, I 6.Bell Transformers FOR Collectors of point by means of a spirit lamp or otherfor A.C. 101 volts. 2 6. 230 volts. 5/6and15', source of heat, and by keeping it at that MORSE PRACTICEsvr.Sound Type No. 10, with Key and Buzzer on base.3 -. Visual Type No. 2A with Key and SHIP MODELS temperature for half an hour.It is betterLamp on base. No. 3A Duplex with Key and Buzzer and Lamp for sound and visual, line plug is on base, 7 -. if the selenium just does not melt, but is BUZZERS from 1 - each. We OFFER retained upon the verge of melting for the YOU MUST KEEP YOUR BATTERY PREPARED!!! Battery Charging on A.C'. Mains.The AA'. NITS - above -mentioned time.Finally, the cell isDAY will keep your battery fit without attention. allowed to cool down rapidly.It will then Model N _kg. 105 250 volts A.C. and D.C. 6 8 volts 1 amp.. 15 -. Model N 116. 100 250 volts to D.C. 6 8 volts 1 amp., be ready for use. 25 -.Model N C6. 103 250 volts to D.C.. 6 8 volts 2 amp.. 000 35 -. Model N/1112. 100,250 volts to 12 volts 1 amp., 32/-. We feel bound to say that the preparationDitto. 12 volts 2 amps.. with 6 -volt tap, 66',5 amp.. Cast Waterline Models of selenium cellsis not an easy matter. £410-. PETROL ELECTRIC' GENERATING SETS There are many snags about- the process, FOR LIGHTING AND CHARGING FOR A NEW DISPLAY SET: particularly in the " formingof the cell. £16 ONLY A 500 watt, single cyl.. 2 -stroke. water-cooled,selfoilingStuartTurner and,usually, much practiceisrequired engine; mag. San. coupled to 50/70 FIGHTING SHIPS OF volts, 10 amps. shunt dynamo. before success is obtained. We would advise 1.000 r.p.m., £16. No increase in THE BRITISH EMPIRE, you, therefore, to refer to some textbook price, these are £40 sets ready for immediate delivery. comprising Battleships, Cruisers, Aircraft on the making of these cells, as, for instance. FOR £12. A 150 watt engine and Carrier and Destroyers. Scale 150 feet thelateDr.E.E.FournierD'Alhe's dynamo on similarlinesbut "Moon Element." coupled to 25/30 volts, 6 amps. equal I I I dynamo. inch. Set of Models. Half Kilowatt and other sizes; all reads, for immediate To construct a simple " coppertype ofdelivery. Price 4/ - photo -cell, you require merely to immerse inSTORAGE. You may have charging facilities and want to install high capacity steel accumulators which will Also obtainable, a comprehensive collec- a very weak solution of copper sulphatehold their chargealmostindefinitely. A.R.P. EDISON HIGH CAPACITY STEEL CELLS at tion of cast models, 100 feet equal I inch. two copper strips bound together with a half price for stand-by lighting, 120 A.H. to 300 AILat piece of ebonite or other insulating material 20.- to 25 1-. Makers' Price is £5, Ask tor leaflet. FULL All Types of THE BRITISH NAVY. PARTICULARS gladly given as far as we are able to between them.The immersion should be A.R.P. ENQUIRIES. A.R.P. ACCUMULATORS for stand-by H.T. at 6e1. I continued for about a week, during which Send stamps !,d.for Price List per volt: 3 amp. hours. In 24 volt unit crates, glass cells. time, a thin film of copper oxide will be 12 - each. Can be parallel charged off 12 volts. ELECTRIC IMMERSION HEATERS.Save coal. A. J. HOLLADAY & CO. LTD., formed on- the metal surfaces.If, now, theArmoured bath or tank type with flex.1,000 watts 230 metal strips are connected together in an volts, 25.-. (Desk P.M.) Fuggy Dug -outs or ill -ventilated shelters must be kept external circuit and a strong light is allowed fresh. 3, Aldermanbury Av., London, E.C.2 A.R.P. SHELTER Ventilation and Air Conditioning. to fall upon one of the plates (the other Compact unit, drive off A.C. or D.C. mains, 80 watts: being kept more or less in darkness) a small 9in. Blower, 20 cub. ft. fresh air per min. 251- is a bargain price. current will flow.Such cells, however, are WET WEATHER ELECTRIC PUMPS, for A.C. o. of little use.They soon fail in use and, D.C. 12 v. to 230 v. Centrifugal all -bronze pump, throws In WORKSHOP and HOME 120 gals. per hour. 72 6. Type R pumps. Twin piston type even at the best of times, are erratic in for draining shelters, dug -outs, etc.. £13 17.6. behaviour. You could not make a cell from RADIO SIGNAL 'PHONES. Complete sets with 5 line keep warm with a PORTABLE or 20 line exchanges. cuprous oxide powder and copper. Portable army wardens 'phones, etc.State wants. Modern photo -electriccells are of two POCKET HEADPHONE -S.W.D. all leather types -emission and self -generating. The headband, strap and cords, 31 pair. Wireless TILLEY RADIATOR type, with aluminium headbands. 3 9. 4,000 latter type of cellsare,as their name ohms, 4 6. 6 6 and 86. LISTENING MIKES. steel clad Electradix. The un pieasant conditions o. wince. implies, used without a local battery. The indestructible; are ears outside your dug -out. aresoonforgottenamidstthe former cells, however, require the assistance ('ABLE.Lightweight twin field cable, unbreakable comforts of the home. The Tille> Army steel reinforced. 55 - mile. Heavier types. 65 - and Radiator beingPORTABLE,pro- of a suitable positive potential to collect 70 vides warmth in workshop, sitting FIRE CONTROL SIGNALS.Emergency day Lucas the electrons emitted from tie cathode. and Aldis Hooped Army Signal Lamps, telescopic sights, room, bedroom, bathroom,etc. Usually, however, the emission types of hand or tripod. For Fire Brigades and Police, 60/-. .srequired. Burns ordinary Alit RAID SIGNAL BELLS --FIRE ALARM BELLS. paraffin at the low cost of Id cells are, for ordinary purposes, the moreWatertroof mains, Battery or Hand magneto Butters; .or 6 hours.Requires no con satisfactory and robust in use, despite the Morse Practice Sets.Morse Keys.Recorder gear, as previous adverts. nections or fixing. Absolutely safe fact that they only give a current of a few5'- EMERGENCY PARCELS of useful No wicktoad ustandcause stand-byelectrical and radio repair mater- neither smoke, suetno' me - microamperes, whilst a self -generating cellial and apparatus, 10 lbs. fors' -.Post Free. British made Price3T8, plus S will deliver up an almost equal intensity Don't forget to send for latest Bargain List

Old05 Ol onn,ogers of current.Cells of this type. _of course. Stores itan, difficulty,write to:-- eninot be home-made. but they are cons-ELECTRADIX RADIOS increiallyobtainablefromtheGeneral 218, UPPER THAMESSTREET, LONDON, E.C.4 iILLEY LAMP CO. (Dept. P.M.), HENDON, N.W.4 Eleetrie CoWembley Telephone:Central 4611 144 NEWNES PRACTICAL MLCHANICS December, j939 A SHEET OF BLACK PAPERBUY, EXCHANGE or SELLAUTHORITATIVE TOOLS-Continued SendforMy LatheLists.-L.MArrunvs, 83, Shrewsbury Road, Forest Gate, E.7. TRAINING BRAND NEW POWER TOOLSofquality, 10 -inch bandsaws, 54/-; Jigsaws, 22/6; Bench Drills, A TUBE OF 11/-; Ciiculat Saws from 25/-; 3 -inch S.C. Toolloom Lathes, from £4 5s.New 1 -inch chromium plated, in Wartime Micrometers, 12/6; Electric Drills, 37/6; Grinders.- John P. Steel, Bingley. In peace -time the T.I.G.B. home -study courses GRAYSON'S Glass -boringOutfits..andTube. Cutters avoid risk.-Below. provided first-class technical education. For DRILLS, Taps, Dies, Files, Chisel. Punches. severalyearspastthepasspercentageof Best quality at keenest prices.-Grayson & Company, T.I.G.B. Students at Professional Engineering 300 Campo Lane, Sheffield. Examinations such as A.M.Inst.C.E., Finest quality Tool Steel Round Blanks and Short A.M.I.Mech.E.,A.M.I.E.E., A.F.R.Ae.S., Pieces, I" to2i" Dlam.,easily hardened in ordinary tire. C. and G., etc., has not once been lower than Originally cost over 1/- per lb., while stock lasts, we96%-and no fewer than 22 FIRST PLACES are clearing at 28 lbs. useful assortment,5/-rarr. for.-have been gained.In War -time the advantages Below. of T.I.G.B. Training-free from black -out and MEM For Re -grinding Cutters, Taps,Drills,etc. Thin travel difficulties-are most marked.To -day, Fine Emery Wheels, ii,r" to j"Thick, 21" to 3" diam., The T.I.G.B. courses are the ideal method of 2" hole.These wheels will be found extremely useful ECONOMICAL ANTI -GLARE for Tool Jobs.Clearing at1/9per doz. assorted.-qualifying quickly for the great range of posts Below. being offered by Industry and the Govern- 85 Machine Vices for Drilling or Milling Machine.ment to technically trained engineers, the LAMPSHADE FOR Robust design, Width of Jaws 22", opens 32", veryneed for whom, needs no over -stressing.Write cheap to clear, 4/9 each.-Below. TO -DAYfor"TheEngineer'sGuideto 2/9 any lot.Eight lots 81.-Below. Success," containing the world's widest choice Toolholderwith four H.S. Tools. of engineering courses covering all branches and 1"Adj.Boring Tool with H.S. Tool. recognised qualifications.Mention branch, post A. R. P. IV to A"Silver Steel,13 pieces,13-long. to 2"Silver Steel,4 lb., 2" to 4' long. orqualificationthatinterestsyou. The 100 Steel Hex. Bolts and Nuts,r to r. T.I.G.B.guarantees Ste -Fix is the neat, clean, 16 H.S. Drills,1/32" to 8)32". training until success- speedy way to do a strong, Slitting Saws, five 1/32' to i" thick,I' hole. ful for the one fee. lasting job.Colourless, Two dozen Fine and Odd Thread Taps,to I". odourless,needingno Three dozen Tungsten Hack -Saws,to 12". The Technological itisapowerful 18 Grinding Wheels,r to 1" diam. heat, Three H.S. Tap Fluting Cutters,II'diam. of adhesive and spreads One dozen Ass. Files,4" to 12". Institute straight from the tube. Dozen Toolmaker's Needle Files,indispensable. Great Britain 2d., 6d. and 9d. the tube. Best Carborundum Wheel,6" by i" by r hole. Made by the proprietors 200 Springsto approx. 6" long. 218 Templeple Bar HouseE.0 ofStephens'Inks,57 Four Ass. Carborundum Wheels, to Q'diam., r hole. London- - .4 Burke. --Below. Aldersgate St., London, (Founded 1917) E.C.I. 12 Sets Stocks and Dies, etc., Split Dies,cutting 3/32",11", 5/32", 7/32", 4", fe, Whit. or B.S.F. 20,003 Successes or 0, 1, 2, 3, 4, 5, 6.B.A. Complete with Taper Taps, AdjustableTap Wrenchand Die -Storks. Seven Dies and Taps, usual price of these sets is 12/6, clear while stock lasts at 6/6 per set, extra sets of Taps, Seconds or Plugs,1/9set of seven.-Burke. HAVE YOUR OWN Small Taps,7, 8, 9, 10, 12 B.A.; IV Whit.6d.each. No dies these sizes.-Burke. An Absorbing Hobby CINEMATOGRAPH SHOW 1"Round Dies,Screwing 2"; -A-; r ; r Whit., AT HOME The New 11.S.F.; or Brass.26 Threads; Set of Five Dies 2/9; BUILDING A STUART MODEL IS "Homray" Best Quality 1" Die -Stocks, all Steel unbreakable with Projector Hardened adjusting Screws,1/9each.-Below. AN ENGROSSING PASTIME, AND 4,000 Taps,Taper, 2nd or Plug, same sizes and Hand Threads as Dies, 2/9 set.-Below. THE RESULT A CONTINUOUS Turned YeeBlocks and Clamps,Starret pattern, accurate, Model first-classfinish,15/- pair-Below. PLEASURE £1 orders carriage paid, except abroad. J. BURKE, 30 TRIPPET LANE, SHEFFIELD, 1. 271 We illustrate: Mains Motor STAMPS STUART Driven Model FREE!! Twenty Unused Colonials."Neurope,' NO. 10. (Universal) 1!/.,d. Fifty for 10'e d.-G. H. Barnett, Limington, Somor,c t. High Speed £3.17.6 Steam Engine. Obtainable from tradtreg Stn,es and Photographic Dealers Write to -day For illustrated list, and name of nearest stockist Bore :"1". HOMRAY PROJECTOR COMPANY (P.M. Dept.). 46 High Pavement, Nottingham Stroke 1". VOYLES Each set is quite BOOKSELLERS TO THE WORLD complete- NEW MODELS drawings and instructions are A.C. Motors.Sell NEW L SECONDHAND included. Starting. Switch built in. H.P.53/- TECHNICAL BOOKS If you have a lathe- and boo'cs on all other subjects.Stock of The rough castings 1,440 R.P.M.200/ nearly three million volumes.Catalogues 8:6 250V. Universal free on mentioning your interests If not- JOIN THE SCIENTIFIC BOOK CLUB Fully machined set- - - I 8/6 Usages. Ditto, with all holes drilled GRINDINGAND 113-125, CHARING CROSS ROAD, W.C.2 POLISHING UNIT and tapped - - - - 25/ - 1/10thH.P., A.C.-D.C.,100 Telephone:Gerrard 5660 (16 lines) or 250 Volts,5,000r.p.m. 11111111Moww, This andmany other Stuart engine: are Fittedwith 4in.Mop, Sin. Grinding Wheel, Guard fullydescribedinthe72 -page CATA- andTool Rest. Built-in LOGUE No. 3, 6d. post free. Switch and 4 feet of Flexible Cable. PriceV/ /9/6 Plush) %Increase...1'f PERFECT USED MODELSSTUART TURNER LTD. SendCd. for our Railway Catalogue and Save Money 18 P.MT.:leBrthiox.teon itRdai.l..oenedloon9,3S.W.9 HENLEY - ON -THAMES EASCO GEORGES', II, Friars St., Ipswich BUY, EXCHANGE OR SELL Advertisements are accepted for these columns at 3d. per word (minimum 12 words at h.-advertisements of less than 12 words are charged at the minimum rate of 3s.) subject to a discount of 2f% for 6 consecutive monthly insertions or 5°,-, for 12 consecutive monthly insertions. TERMS :-Cash with order. Cheques, Postal Orders, etc., should be made payable to George Newnes, Ltd. The Proprietors reserve the right to refuse or withdraw advertisements at their discretion. All advertisements must be received on or before the 5th of the month preceding date of publication and should be addressed to the Advertisement Manager, " Practical Mechanics," George Newnes Ltd., Tower House, Southampton Street, Strand, W.C.2.

CANOES MICROSCOPY-Continued WIRELESS BOATS AND CANOE KITS.Hobby for long "THE MICROSCOPE AND ENTOMOLO- HEARAMERICA, AUSTRALIA, JAPAN. - evenings.Prices unaffected, few bargains.Metacraft GICAL MONTHLY."-Thepremier journal forall Receivers 19/6.List, W. Buckle, 63 Avenue Approach, (P) Christchurch, Hants. students of nature. 1/-, from newsagents, or 1/1 from Bury St. Edmunds. Microscope, 20/21 Took's Court, London, E.C.4. ELECTRICAL AC/DC MOTORS,1/12.03 to 1/8 h.p.,from 10/-. MISCELLANEOUS 'stamp particulars.-Brookes, Banners Street, Cradley, MODELS BE TALLER ! Extra inches count !!Details Staffs. PERFECT USED MODEL TRAIN BARGAINS. 6d. stamp. - Malcolm Ross, Height Specialist, Scar - Popular makes.Send 4i/2d.for our catalogue and borough. save money. --Below. ENGINEERING CASTING MOULDSfor Lead Soldiers, Indians, Animals, etc. Sample mould, 2/9. Catalogue stamp.- METAL FOR THE MODEL ENGINEER. FOR TRIX RAILWAYS. Some special 4-4-0T Industries 2, Waldegrave Park, Twickenham. Sheet, Tube and Sections in Aluminium, Copper, Brass, locomotives and wooden coaches; particulars1 !Ad. TELESCOPES, etc.No quantity too small.Stamp for lists.The Exchanges.-Georges', 11 Friars Street,Ipswich. MICROSCOPES, Scientific UniversalProductions. RigbyLane, Brornsgrove, Instruments, etc.Send for lists.Sale or Exchange.- Worcs. C. V. Bolton, F.S.M.C., 49a Leigh Road, Leigh, Lancs. METAL WORK MODEL AIRCRAFT PETROL ENGINEScomplete, £215s. 6d. or ready PATENTS AND INVENTIONS MAKE METAL TOYS. Easy, profitable with machined assembly kit, 395. 6d.Timers, propellers, WE SUCCESSFULLY SELL 'Success" Moulds.List free.Complete trial mould gas and rubber kits.List Ii d.-Lowe, 10 Lindbergh inventions, patented 1/6.-Lee's, 1 Birkin Avenue, Nottingham. and unpatented.Write for proof, and tell us what you Road, Bournemouth. haveforsale,-CharteredInstituteofAmerican Inventors, Dept. 16-C, Washington, D.C., U.S.A. MICROSCOPY MUSICAL INSTRUMENTS MICROSCOPES, Telescopes, Glassesand all NEW RECEIVERS Optical Instrument repairs,etc. Dept. 2:Lathes, BAND GUIDE.Hints on the Bugle, Drum, Flute Files,Saws, Emery Grinders, Engineering reivire. StaffParadeformation,etc. Free,postpaid.- "STAND-BY"CrystalSet (See August issue ments, repairs general.-Mackett & Company, Manu- Potter's (Manufacturers), West Street, London, W.C.2. " P.M.").A useful and good Receiver.Aerial coil facturing Opticians and Engineers, 51 Millers Road, 2/3. Detector 2/3. Complete kit of parts to build 10/3. Brighton. 45ft.copper spiralaerials I/3.-Thompsons, 176, Greenwich High Read, Greenwich, S.E.10. WORM DRIVE PHOTOGRAPHY PHOTOGRAPHIC MATERIALS.Plates, films, JUBILEEHOSE CLIPS mounts, chemicals. Interesting motley -saving lists TOOLS The long -life clip with free.-" Kimber's," 105 Queens Road, Brighton. MYFORD LATHES have no equal for sturdiness the ever -tight grip. and value.Lists free. Delivery anywhere. Terms still SITUATIONS VACANT available.-Nuttall's, 20, Albert Street, Mansfield. The Best Known G.P.O. ENGINEERING DEPT.(no experience For Radiator Joints, required). Commencing £3/13/0 per week. Age 18-23. Mr, Oil, and Water Excellent prospects.Free details of Entrance Exam. A GOOD PIANIST IS from B.I.E.T.(Dept 570),17-19 StratfordPlace, Hose Joints. London, W.I. ALWAYS WELCOME We guaranteert a Tight nxsv to bei.oine a really FINE PIANIST and SIGHT READER, I willteach YOU quickly and enjoyably BY POST, from WATCHMAKING ordinary mutic (aof reakish methods) enabling Stocked by all Garages you to read and play at light any standard and AccessoryDealers WATCH & CLOCK REPAIRERS. Send 3d. for musical composition So that you shall give complete list of material and tools.- -Blakiston & Co. delight wherever you go. No practice drudgery, L. ROBINSON & CO., Ainsdale,Southport - but simple, interesting training a and could follow. A teacher by yourside always, not for merely half an 21 London Chambers, hour weekly. I have taught over 51,000 adult GILLINGHAM, KENT. pupileduring 35 years and I CAN TEACH YOU, even if you do not know a note. Proof-Advanced 49171, Ape 313: "I hare praremed for beyond the bounds of 358 in.WINFIELD my imagination,"Send for free booklet "Mind, FOR VALUE AND RELIABILITY Muscle and Keyboard." and form for free advice. Say If Advanced. Moderate, Elementam or Beginner. iadui"666471illill44: Mr. II. BECKER c) Brilish by Birth and " Baker's " Solderine.For al electricalwork and wherever Descent) paste flux is preferred. Popular (Dept. 258), 69, Fleet St., London, E.C.4 sizes include : 2oz. tins, 6d.; 4oz. tins, 8d.Also supplied in bulk. assay maue scorn our glib,Obtainable from all castings 12/6 per net. wholesalers. Complete Engines u. readytorunfrom £.3155. As illusiratea EIO - 10-0 1. HALLAM & SON or by 12 monthly payments of 18 4 Upton, Poole. 3in.B.G.S.C. Lathes from E4 - 10 - 0 Dorsec S tANT/(yik s MINIAl L) it I PE IRO!. ENGINES . . . for aERIN The Winfield Mfg. Co.c o Aeroplanes and Speed Boats. 1 to 15 c.e. Sir%&MM 1.(.0 Send 3d. for particulars Great West Rd.IsIssawili PASTE .1.1.1/1 414176 ----CUT THIS OUT - Practical Pen Coupon Value 3d. MAKE MORE MONEY OUR ADVICE BUREAU Send five of these coupons with only 3/-(and2d.stamp) £3 to £6 weekly can be earned at home in a wonder- directto the Fleet Pen Co., 110, Fleet Street, E.C.4. ful business of your own. No matter where you COUPON By return you will receive a handsome lever self -filling live you can commence to make money in your This coupon is available until December 30th,1939, FLEET S.F. PEN with solid gold nib (fine, medium, or spare or whole time.No risk, canvassing or exper- and must be attached toallletters containing broad), usually 10/6.Fleet price 4/3, or with 5 coupons ience required. A wonderful opportunity for anyone queries, together with 3 penny stamps. A stamped DeIslasModelFLEET SELF -FILLER, wishing to add pounds to their income.Particulars, only3/-. stamp. addressed envelope must also be enclosed. 2/- extra. BALLARD. York House, 12 Hambrook Road, PKAC I ICAL MECHANICs, DEC., 1939. LONDON. S.E.25.

All applieatunis respecting Advertising in this Publication should be addressed to the ADVEkTlSEMENT MANAGER, GEORGE NEWNES Tower House, Southampton Street, Strand, London W.C.2.Telephone'Temple Bar 4.363

t '%itrr* Ideal Christmas Gifts at Bargain Prices4#9et.7e . 32 Page Christmas GiftsList Sent Post Free on GAMAGES Request BRITAIN'S BIGGEST VALUE IN TOOL CHESTS AN EVER -POPULAR GIFT sHI FCF IHE EL sl3T MADEFRT O OL S IN ONLY

Contains an extremely comprehensive range of fine quality tools-suitable for practically all woodworking jobs. Chest stained and polished Walnut colour. Size: 27 in. by 11 in. by 74 in. Fitted with fixed compartments for small articles, and movable tray with 24 spring clips tohold chisels, bits, etc. Contents: 1 Skew -back Handsaw, 22 In.;1 Tenon Saw, 12 in; 1 Set 3 Blade Compass Saws; 1 Pad Saw and Handle; 1 Smoothing Plane, 2 in. double iron; 1 Joiner's Hammer, No. 2; 1 Claw Hammer, No. 1; Joiner's Mallet, 5 in.; All -Steel Hatchet, No. 1; 1 Cased Oilstone, 8 in.; 1 Joiner's Square, 6 in.; 1 Sliding Bevel; 1 Spirit Level, 6 in. ;1 Spoke- shave, 24 in.; 1 Marking Gauge; 1 Cabinet Turnscrew, each 4 in., 6 in., 1 pair, Pincers, 6 in.; 1 Handled Chisel, each } in.,in.,in., 1 in.; Handled Gougein.; 1 Joiner's Plain Brace, 9 in. 1 Centre Bit, eachin., in., 4 in.; 1 Special Auger Bit, each } in., 1 in., in., f in., t in.; 1 Boxwood Rule, 2 ft. ; 1 pair Combination Pliers; 1 Putty Knife; 1 Paint Scraper; 1 MitreBlock 9 in.; 2 Gimlets; 2 Bradawls; 1 Glue Pot; 1 Cold Chisel, 6 in. byin; 1 Tack Hammer; 1 6 in. Half -round File and Handle; 1 4 in. Saw File and Handle; 1 Centre Punch; 1 Nail Punch; 1 Packet of 12 Sheffield Twist Drills; 1 Pencil.

Carriage (outside our extensive delivery area) Or DELIVERED on FIRST of SIX MONTHLY PAYMENTS of 15'6 3/- extraEngland andWales. with Compound 21" PLAIN GAP BED LATHES 11" PLAIN GAPBED LATHE Slide Rest Will stand the hardest usage by hand or power. Possess many Overall length, 12} in. Length of refinements usually found in larger or more expensive tools. bed, 8 in.Maximum distance Length between centres 10 in.Face -plate 31 in. between centres, 64 in.Height diem. Height of centres from Gap 21in. of centres from gap, 2 in.The Slide Rest with Vee Slide, Square nose of thesolid mandrelis Thread Lead Screw.The Head- 1 in. x 20 in threads.Bearings stock Hollow Mandrel is boredin. adjustable for wear. Compound Mandrel nosein. x 16 in. threadsa sliderest has vee slides with and bored No. 0 Morse Taper. Cone gibs and adjusting screws. Pulleys 2} in. and 1} in. inside and Tailstock is of the sliding barrel 21 in. and 1/ in. outside. Lead type, and is held in position by Foot Motor, 13/6; Screw 1in. Square a set screw.Driver plate 11 in. a Carriage (outside our extensive delivery Countershaft, 15/6; Set of thread, 12 dia. Cone pulleys 1} In. x It In. area)1/6England or Wales. 6 Tools, 3/-: 3 -Jaw Dog Chuck, Weight of Lathethreads. 18 lb. 37/6 dia. for to in. or in. 6/6; Belt, 2/-.All above carriage Carriage (outside our extensive de - round belting. Weight Accessories as for 37/6 lathe extra if ordered separately. livery area)2/-England or Wales. 8 lb. 21t on left. Exceptional Valuein GEARED Hign-tirade BENCH GRINDERS Hand driven, fitted 4 in. x fin. wheel MINIATURE A.C. MOTORS (50 cYcles) and with toolrest.Strongly made Will work through any suitable transformer. Rating throughout, it will give years of ser- 12 to 14 volts continuous to two minutes at 24 volts. 5 :--.6 vice. Offeredatabout half the expect topay. Incorporating bi-metal thermal cut-out and auto- a price you would maticclutchtoavoidbreakageunder sudden .41( Post 7d. stoppage. Reversing switch, self-lubricating bearings. Rotor speed (no load) 2,000 r.p.m. i*lit Output spindle speed 58 r.p.m. All fi h.p. CAPACITOR START MOTORS brand new, and remarkable value. by a Prominent British Manufacturer Post 6d. I ' illustrationis approx.one-third Originally listedat 4 gns. actual tire. Te. ''''-'t [al' 111111 Can be runoff ordinaryelectric BOXES OF TWELVE light point. Will drive up to a 3 in. lathe, drilling machine, water pump ASSORTED FILES for garden fountain, or any type of The best and cheapest way to buy Files. lightmachinery. These motors Britishmade andexcellentquality. have had only a small amount of use, Sizes 6 to 12 inches. and will give long and trouble free service. 1/6h.p.singlephase,

1,425 r.p.m.For A.C. mains only, 12 for. 4!6 200/250 volts 50 cycles. Post 9d. Carriage 1/6 Also sizes 4 to 8 ins. 12 for 2/11.Postlid. England or Wales. 251 FIRST QUALITY HEAVYWEIGHT 3 in. SCREWCUTTING LATHES (BACK GEARED, GAP BED), SLIDING, MILLING, SURFACING An opportunity to secure a high-grade lathe at a remarkably low price.Be advised and order now while stocks are available. SPECIFICATION Exceptionallystrongheadstockwithadjustablebearings. Heavy, solid bed ensures accurate work.Machine cut change wheels for all English threads.Saddle and slide have large bearing surfaces, and the tailstock is of rigid design. Swing, over saddle 4} in., over bed 6 in., over gap 8 in. Diameter of mandrel in., mandrel nose 3 in. x 12 threads.Mandrel and tailstock bored I in. clear.Centres No. 1 Morse taper, leadscrew in. x T.P.1. Cone pulleys 3} in., 3} in., 21 in. x / in. Back gear ratio 30 to 20 distance between centres 12 in., overall length 27 in., weight 52 lb. Com- plete with fare plate and ten change wheels. '6 MADE Or DELIVERED on FIRST of SIX MONTHLY PAYMENTS of 14./9ID ND BRITISHTHROUGHOUT Carriage (outside our extensive delivery area) 3/6 extra England and IV ales.

GAMAGES, HOLBORN, LONDON, E.C.1 Phone your order: HOLborn 8484 City Branch: 107 Cheapside, E.C.2 Published .ibout the 30th of each month by GEORGE NEWNES, LIMITED, Tower House, Southampton Street, Strand, London, W.C.2., and Printed in England by THE SUN ENGRAVING CO., LTD., London and Watford, Herts.Sole Agents for Australia and New Zealand-Gordon & Gotch, Ltd.Sole Agents for South Africa-Central News Agency, Ltd.Subscription Rates :Inland and Abroad,7s.6d. per annum. Canada, 7s. per annum. Registered at the G.F.O. for transmission by Canadian Magazine Post. i4