1953MNRAS.113...67S installed constant on at inc National giving Service, lc, 3 took Q3, clock, Physical Meacham essentially regenerative Branch A standard relating fundamental where long-term was of standards signals, secondary established. Observatory, G Group © BR 99'3 orporated group the phosphor-bronze 1. Clocks It QU rendered virtually rendered Royal methods convenient the tabular work advance General was an radio pendulum it kc/s. ART 4 Laboratories. A and which to Greenwich Laboratory temperature of at proved Physical output pattern, of performance Astronomical now bridge clearly desirable clearly a general at employing standards these performance, form. Greenwich time CLOCKS Z simplified three upon in dividers crystal in so by an The The in description.-The were a criterion this that of which its of progress external clocks clocks simple account signals, and that (2) such Time divider Laboratory The 500 first the place also frequency regarding pins respect the (Communicated having (4) by were of G T were clock obsolete version of cycles degree The Society greatest Service, three available oscillators, some in Service supplemented is to Pierce with means into is and and these -cut establishment. (Received thus among chain OF proposed. that eeoe independently developed brought be given 1939, performance oven also Humphry five per good a of in mounted clocks a two plate of was ( communicated view rnig about bringing clocks as THE and • I oscillator similar quartz clocks quartz similar value. stability of I would performed I942 ) years sidereal of first the the Provided to . the a Summary and and by similar 1 kc/s the 100 a 95 known day-to-day long-term standard long-term the to into the crystals This the 2 thermostat supplied mercury superiority was Quantitative arrangements ago. standard GREENWIC improving present quartz November by M. temperature-control not was development kc/s, may output in now Within Astronomer Time use second circuit, so quartz data There Smith by employed an be as Details successive be attained of markedly early in which the NASA the installation evacuated entirely dependent Service daily "Group clock thermometer. by. received stability studied used a a pendulum the a stability 13) to designed clocks of and considerable drive was year results in Royal) are the drive of TIME H was to represents were the pattern 1944 of to a should at given was the also superior that are division Post it the 4 (6). daily circuit Q2 Astrophysics still ring is converted for drive quartz the the a " are glass became made described. quartz by described for phonic designed of clocks the and an Royal further. (5) arrangements the Office Post developed presented crystal be from development Observatory Turner significant a the a The vessel urgent improvement SERVICE based pendulum by to attained Q6. for clock installed clocks phonic control upon clear control motor. of even Office Observatory> 3, the by were and information crystal to Data The supported. the 6 (3). held upon had means National .oscillate need of in that primary and 5 the a at motor. * a of of Radio at Time of System clock This were high been at The was was· best the the II, the the the the the for of In a 1953MNRAS.113...67S ()8 the these to mains to were were uninterrupted and This -could observations; station phonic sidereal functions accuracy various however, become possible become Greenwich, was inferiority -comp'arison failures may Two means particular, to to by performance employing between the one either of dently on possible oscillator. inapplicable piers, it The © the was base disturbance connect During top fully an One day-to-day As Royal control rack, power found be mains temperature-control clocks designed overcame similar Post electricity be decided thus at G T improved of the ntal installed, initially of motors above this gearing result conveniently forms electronic to Abinger were standards of the provided in Astronomical hitherto of Office 1945 a it service or GT-cut equipment, the operated maintain making as to supplies New equipment accordance the and. was to pier, at the became precision grollpS ring clock of still to to long-term and fQr of uniformity the be were dividers the edlm clocks. pendulum were the four supply quartz for the the re-mount pendulum provided incorporated Group crystal (7). Post where time on crystals. incapable battery decimal dependent carried directly runs time. oven. crystals more it by main the others widespread and groups were a used developed intercompared of necessary the possible These Office constant Society which means together were beat with signal clocks quartz 4, and it were three ovens standards the that, Post unit elaborate cause is to of operation, out were the of automatically re-arranged counter from clocks are of Some protected The of standard phonic motors phonic oscillators, of comparator provide Humphry the three these made on specification had and of oscillators Office distributed oscillators to under three by available some • frequent were clocks to not installed check with meeting employment in of group Provided a 50 a oven the rotary carry replace been the led maintaining was chronometers minor order oscillators time unduly possible. disturbance Relative timing with oscillators, constructed a Group sidereal quartz minor and war-time cis to Post to from on pendulum .. is stand-by M. seriously to out adequate together occurrence. for perform, beat in In their located a.c. by signals. singly the ( great the each that by an the 10 permit by changes Smith Office which new sensitive accidental the work devices, to 4 a direct improvements. clocks ) rates supply, the NASA the of extensive seconds performance new counters The complete of electro-mechanical standards. the battery-driven and all course conditions, those accuracy on were amplifier similar quartz clock diesel with to in impaired in each practice. for (9). on clocks: with is convenient eurmns of requirements individual Unfortunately, may temperature-control Department, demands practical a the (8). integrated were the to capable and one designed use hollow oscillators giving oscillators subsequently It their cellars for disturbance of generator, group clocks in Moreover, Astrophysics greater installation mechanical ( elimination. be was oscillators, Observatory II the by with are in oscillator Motors the general made in by ancillary ) of interruptions readily Although . necessary the methods thus at in use. brick for mounted fact, of astronomical was were the motor all Special pendulum isolation It accuracy, to the time a event producing made oscillators in was concrete still accuracy. fact arrangements thus incorporating that chronographs and accommodate quartz the the Obs and obtained one on mounted It without disturbance, of equi installed and the Data the alternator. differences workshop, necessary which provided. oscillators re-wiring, that had draughts. of the batteries Vol. types value manifest ervatory indepen becomes circuits, concrete the the p of service longer of all mains ment, circuit System clocks clocks clock block they time thus each best II3 the and full risk the the are by of In of at 1953MNRAS.113...67S No. 1951 disturbance rod. association arrangements: constant-temperature warning the toroidal loading modified seconds. long-life proceeded necessary oscillators, by the temperature-control substantial long-term Very perhaps immediately was performance same drift. drift, A degree reach from ment recent performance valves mixing attention. sensitivity replaced pattern accurately transformers. operated of may power remarkable © identical In nickel The crystal amplifier 1, installed Royal . in be high service, which type, the The 1953 experience. view One of w further Two of of is were short-term transformers employed valves. of the ancillary connected by to high at Duplicate to ten. used, the pins. Astronomical spaced standard, supports, stability, with to period values forming to reduction The impending E6, plug-in of improved of low amounts devise facilitate of as most will at feature gain changes was and previously roo these, standard produce In the high-stability The and the the GT-cut the was regener anode During Later be seconds Quartz kc/s of of equipment the the still stability, adversely a significant new units, thyratrons the The Observatory temperature in the excellent working and correspondingly but circuit units its of installed C5, ring-crystal the large Q arms are to of servicing. models maintaining new output. in cascade this less thyratron of current, oscillators, Society Post number plate a techniques a useful (i.e. only new the in the tive is oven-control is clocks employed pulses, valve each operated the function bridge of n�mber particular performing pattern, the and sensitive characterized was testing initial sharpness Office crystals, run I affected standard dividers the components other associated a results developed characteristic were giving run latest to of part Some there characteristics. • few of with new in increased control. control bridge oscillators of The Provided failure, the circuit perform 1950 transformers forming amplifier for with frequency ring fitted, began Group and and no at of this in months type improved. to is pulse one standard G the achieved consequent amplifiers providing by cycle 10 step-up alignment satisfactorily, ES. good metal metal r nearly of variations setting-up oscillators. e precautions oscillator equal May, at with en 8 output Post with and the suitable valve by only were resonance) by per dividers to 5, In wi the frequency Group was reason were of For was later, ch rectifiers employed the NASA the rectifiers ring a improve drift. is Office separate signal lamps, and the permitting the reliability year. full ra Royal with the a has have were the uniformly employed, Time pulse In ageing. an thereby tio modified and subsequent week saving installed shows in is of oscillators new was to for and have order small new 9, output been rated It have but Radio of suspended a been An suppose re-wound supply these A Observatory. adjustment. Service have for division was utilized are the brought a and bridge has or Astrophysics the ring second maintaining been the a at of ring reduced oscillator reduced value every ring been to The replacement satisfactory improve satisfactory fitted anode employed, accordingly in Branch so oscillators changing sensitivity, and towards any at been power exhibited transformer a other, crystals meet voltages designed. employment that has the after oscillators I total softer by of drive ten crystal. taken valves oscillator on input illto on the kc/s with the obtained, light to the to also current, Laboratories any a the input and C6, silk of installation. of thus layout the The solid four. use Data about supported have amplifiers frequency frequency prototype long-term circuit it to metal or electronic frequency this a removed are need and fourteen received failed required of threads. without reduced became A similar render end almost in pulses, giving in Three earlier is of System brass· series. more been type as The now wa five and but the the the the the for for in to of s· a 1953MNRAS.113...67S © 70 from thus uniform provides therefore used of long-term .based the Royal introduction different Time attempt difficult ultimate from by that fluctuation time, fluctuation fluctuation Observatory investigators. advantage U.S. annual of impracticable astronomical the be annual established reference the to determine two establishments observations Observatory to five its the 2. The The the determined uniformity the use The highest taken the as lOO or polar Astronomical Naval Assessment it magnitude such Service on ( rotation (b) analysis fluctuation a Earth; on of fluctuation. working problem clocks to has ) three aspects. sta application effect 000 seconds necessary independent to would from prediction. from of an units the account observed remove ndard motion, in over by precision. Observatory. been the of to the made pulses is time average of of the to taking The rate years. was which of to from performed improved apply month this to supplied day general a be the are extremely high standards of of obtain pulses the define of the is rate number Society bevtos provisional observations use of of to over degree the sensibly gained or in relating long-term to per time in subject subject disparity time, the the Earth. A value the current adequately the mean clock mean the assess practice practice accuracy data more The day preceding of to Those But a effects a trend an second time of time a with mean latest scale clocks mean time month rotation for of by • the sufficiently uniform sufficiently over Another high in extended of derived more such may constant procedure to to the Provided the briefly, agreement Humphry the It pulses the corrections observations performance.-For scale of the years of of has with rotation scale provided of appreciable considerable for developments the is of a to employing performance stability quality be application the a these over years. fulfil a one period than period therefore control of the scale been one number the misleading from clocks that derived a of known was "polar astronomical period from by by the known a high principles M. the last adequate now best adequate pulse of between by of is period is, the NASA the growing consideration 1950 of of independently variations for It Earth. the of not Smith variation should the first themselves, the year as of five ring-crystal one necessary corrections the cause from uncertainty. degree variation". at has of adopted clocks the in cause nearly per of time-signal specially June clocks a Earth, absolute Greenwich (13). vial clocks available of latest month time requirement years quartz since to correction these a may the accuracy. variation the uniformity second. observations more of The provide two Astrophysics modern year, of to at of of from as has 100 irregularity scale be to This crystal eoe apparent become has at operation at various 195 the irregularity possible, of day-to-day aiue observed latitude years or selected clocks. and mean for oscillators unless determined calibrate pronounced illustrated surpassed the the kc/s and These the year It transmissions. longer. 2 become and based a various in fluctuation by quartz A polar current June. has Full or time oscillators. are Royal Royal astronomical crystal may that amplitude longitude results suggested results series to it Abinger. applying over from Data quartz For uniform, so; corrections in of on can employed year, is the variation advantage scale (12). stability considerable clock increasingly in that fact however by Information a cooperating estimations some the the Greenwich a Greenwich by System frequency consisting these be scale since observed National period reference Vol. clocks can and that become defined average that several arising annual related to of to at and In years It with time only two II3 that and the are· the for the the are the the an be is is is of of to 1953MNRAS.113...67S twelve-monthly long somewhat preliminary and provisional errors the in demonstrated (see of basis relating depended fluctuation clock clock ephemeris polar clocks clear was No. drift: year the the clock independent polar no © annual successive The such period major rate annual made. I, Fig. Royal to was interval evidence was intercomparisons. was variation variation 1953 9C were arising the to five of thus I), adjustment; fundamentally related fundamentally rates, in then upon extending in part each Astronomical all under in next, In fluctuation parabolic uniform clocks which amplitude then of 1951 by considerably available years provided the of the from and referred but of individual given the the periods. it a the review Quartz rate course referred the
April, U w observations, o rate rate combined to was adoption, the in monthly practice the values no two to had of A • PLOTTED. determine NNUAL 1951 of Provided but or in the plotted removed. adopted effect upon effect t readily astronomically he fluctuation. the of years, o been scatter. the FIG. the drift determined adopted interval. astronomical 0 that to adopted Greenwich three May, AT which selection means It for RATES 12-MONTH into residual at were Earth I. of CENTRAL ultimately give two in points accessible IS this the for by each the corrections each and any found a annual of The the NASA the clock a the of time procedure The the performance Where for mean MONTH clock, series the Corresponding of particular adhere Time EA PERIOD. rate. the effect, had observed mean standard uniformity the system determined the system rates that efficacy clocks, from strictly observations, in clock, fluctuation. OF the of Service one of to amplitude five Moreover, 1951 closely Astrophysics and a is clock. the determined intercomparisons the annual the preliminary clock, was effective defined E5 and E5 apparent which best of of eeiie rm one from repetitive ie corrected time of November. largely parameters fluctuation current time. the and by however to monthly the Since lcs These clocks. due rates. and clocks during consideration straight established corrected An 9A, by the in scale from process Data change eliminates over allowance graphs removing the parabolic adequate phase required the use largely points If of which varies mean value System these Each lines gave drift of the the for for 71 of of of is a a 1953MNRAS.113...67S preponderance was were following points convenient and period the to 72 to system so by means The for evaluation the © observational be that a It In a u that .are .secular independent 'standard N proportional increase indicated :and around at control time a Standard June June January January .April .August ·October .November December .November Ring :February ·October July p April o. July August Clamp March May September S May February March December September progressive © ort ilk, present fluctuations Observations I this 1 planets 1 1 Royal f 9 95 scale 95 or Pin 5Gl 1: 2 Sup Plate 1 accelerations the 9 long-period of may 5 ·of or 3 by Astronomical Society one against available Sun. . time are +4 fundamental standard. + +47'II + +4 +4 +4 + +47'2 +47'4 + +45' + +45' +4 +47 +4 +4 +4 +4 +4 +4 +4 +4 to be retardation observations 4 4 47 47 4 E5 R S millisecond 7' 0'08 7'58 6 6 6 6 7'26 6 6 6 6 6 6 6 6 6 in their ' ' '3 ' ' ' ' ' '85 ' '34 ' ' '5 ' '8 departing Abinger satisfactorily 61 6 8 5 9 95 2 92 0 00 2 7 2 16 made would 4 9 3 0 5 0 Quartz 0 4 3 6 5 4 7 1 the which Mid-monthly changes for of ------6 - - -6 - - - - -62 mean - observed motions 59 45' 44, 43 E6 5 7 57 47 53' 48'5 5 7 74'43 6 55 R S 0'10 6 0 4'4 2 7 9 the 1 over '9 ' '32 be ' ' ' ' '47 ' ' '34 this '5 6 9 0 6 06 20 06 42 6 06 clocks in the 7 2 7 4 4 0 8 3 7 from per of motions Sun, provided the Greenwich in purpose many accounted +8 +8 + +7 + + observations +7 +8 + + +77' +77 +78'47 +7 +77, +79'4 +75'4° + +7 +73'9 +74'7 +75'54 +75'78 +7 values tla transits. stellar century (milliseconds of FI 83' 8 83' 8 7 77'3 • C P rate rate 0 0 0 6 8, 2 4 2 6 8' their 2 1 ' '5 ' ' ' '3 '54 '74 , ' ' Mercury Provided the 0 7 8 5 37 61 89 2 85 20 6 62 1 3 3 4 3 2 5 3 6 9 7 1 1 1 of TABLE I TABLE (1"4), years The of and by daily Greenwich predicted is - - -2 in - - - - - - - - - - - - - - - - - - - - - of rotation for 9 2 2 2 3 3 26,6 3 3 3 3 2 2 3 2 32 33' 34' 34 3 3 35' 3 33'4 per the the R P only practicable 8 0 A 9' 8' 0 6 0' 7' 9' 3' 7 0,06 7 the 5' 2'2 1 1 1 rates the drift, '26 ' '5 ' '9 '4 '85 ' ' ' '54 have This 6 01 0 0 6 by 85 21 66 8 23 7 28 6 and 10 1 have 9 7 3 3 0 2 4 7 0 8 by 7 1 day) 1 1 period length rate the NASA the Sun, of tidal - - - - - - - - - - - - - - - -1 - - -1 - - -6 - - Venus A revealed is selected 9 of it positions T 9 0 3' 2'35 5' 2' 0 3 5' 4' 4' 7 6 6 5' 8'97 7 7 9' 8' been 8 Dollis R P C ' ,6 '3 ' ' , ' '8 '22 , '55 '4 ,60 ime of 7 0 6 6 7 84 4 83 2 89 22 1 11 1 1 attributed more is the 3 6 9 5 2 9 9 9 7 9 7 2 7 Moon, Mercury Moon, 8 of friction. of rotation necessary Service Hill the clocks recorded: - - - - - -60 - - - - - are - - - - - - - - - - -6 - - 0 , Earth, revolution Astrophysics 6 5 58'89 58' EA 60 6 62 61 5 57 6 62'26 5 6 5 57 66' 6 6 6 61 66 R 6 uniform 7' 9' 4' 6 5'4 6 3' 3' 5' fundamental 5 4' S that ' '77 ' '54 ' ' by ' ,66 '8 ' ' day, , ' thus 8 0 6 4 7 3 01 2 7 61 60 1 08 1 18 1 1 1 6 3 6 5 9 9 0 4 4 2 7 9 5 1 1 to amounts In amounting of the - - - - - - - - ------ - - - - - - - - - associated an I to 45' 44 4 44 44' 44 4 43' 4 44 EB 44' 43' 4 4 44' 45 45' 4 45 4 4 45' 45 4 addition t the R 6'2 4 2'6 2 6'II 6'2 6'II 1 S 1 the of fundamental ' '11 '48 ' '8 ' ' '5 now ' '9 ' Sun, 62 2 54 error 77 4 7 7 3 6 0 01 57 7 1 refer and 6 7 6 7 0 8 8 9 3 5 8 0 0 1 1 Data the Earth, observed standard that + + + + + + + + + + + + + + + + + + + + + appears + + + N,P,L. Venus, Q 22 21 30'47 2 2 22 23 20 2 26 2 2 1 in 1 1 1 1 1 Moon 1 16 1 1 16 1 to Earth R to System 8'3 5'53 4' 9'5 9' 7 8' 9 7' there 5 9' 7' 8' 7 6' 1 S with ' ' ' '47 '94 ' '45 ' ' ' '84 '4 3 II 62 3 6 0 22 33 7 3 0 1 1 12 1 15 the are 0 7 4 6 0 9 9 2 7 5 2 an 1 75 an as 1953MNRAS.113...67S length been following to arising of orbit to negligible, of recommended of mean between for an the assessment assessed the astronomical accuracy second previously for establish Noon, progress selected but p into Time, recently where the stability Conference rate These the Such 16). er © a continual be cases, uniformity examination I The 3 The the position suitability its variation its day. diff of t time Royal many . is round interpreted variable, The a absolute Assessment the widespread by T of and developments current of relative erence from clearly system second been most in of the is at may the a system from expressi the Ephemeris use It clocks Astronomical Society time scientific accepted but measured uniform virtue B the quartz of on of random may the observed errors in observations. vanatIOns day, pointed of is of be satisfactory from between desirable that may clock the rate value determination. the is U.S. Naval U.S. clearly reckoned of the rate is the 9A the the Sun, unaffected of be secured on: as of + 2 use defined one the Moon for but clocks short-term the to Fundamental be and arising measurements day remarked fluctuation time unit same was clock clock changes. occasional - their performance Time of 48 in may is out be making longitude second of converted . may an unit 34 mean Julian dependent 9C, that the in to smooth, plotted of in the by system, (17) 9 over formula. for indication high by invariable make is intercomparisons the from +7 day. by which second terms Observatory time, the adopted alternatively As the co:mparison specifically three perf Humphry day-to-day extrapolation diff solar that the the centuries 2s·3 that irregularities periods rotation sudden long-term in motions • may This and direct, employment to the it ormance erences and Provided Constants An and the is of 1 sidereal and the besides upon the period there fundamental 6 difference possible time an plotted 5T the this of should use be unit requires example the mean drifts Moon's thus invariable for without M. of + 2 day-to-day changes from of the the of expected, amended intended suggests is with . and unit of of be -It range of stability a those of by year 9 some rqec standardization. frequency Smith in the development provide s· h daily the the in solar of be of month regarded for the 9 of 1900 Ephemeris time the NASA the is alone affords Fig. the will celestial 4 regular the longitude, is the Astronomy 9 the removal the Earth. variable known d physical of a a of correlation T unit, revolution i afforded that second, tabular to d new be 2 tabular 5 rate time-keeping clocks January the also astronomy. should performance . sidereal + several fundamental or a not without provide evident values a I Throughout as the as and satisfactory bodies observations the s· accurate clocks photographic so of quantitative criterion quantitative as exhibit. Astrophysics 8 of These mean exceed of r units, 2IB, Time are places. that rotation Ephemeris which longitude may second interpolation. by an be (Paris, satisfactory 0, milliseconds year between of of a that cumulative sufficiently should ephemeris. reference Greenwich which the employed. unit is, solar clock the a be and is variations observations In o· is observatory is at the unit. high the of Work 5 given relative of the basis 195 satisfactorily the provided of Earth now of 1900 thus millisecond (:14). be Ephemeris second Data day-to-day the technique. rate. the have Time diff this year 0) sufficient standard Vol. majority methods referred. for . now known At by to second similar erence in Earth. effects 0 it enters Mean It Sys(em in kind,. have daily been 19 The The (IS" The was· and II:): the the the the has are the its by 5 of to· in of 1 1953MNRAS.113...67S ::separate ::second necessarily O·, I9S3 NO.·I, diff enhancement time readings sub-sequ RELATIVE other precision and to may as daily by of this mean high daily • the value re-combine It to effect, that is the a Provided the be high the the intercomparisons design clocks after components, should measure of be criterion given than deterioration accuracy rate stability FIG. sometimes grouped which per consideration second cQrrelation. accuracy Greenwich absolute the These criterion ancillary of daily result.. Bm with 9.A given stability between cause of in provides the 5. 13 a day. of ultimate in AND in of quartz by not the the for rates give BETWEEN of modification particular quartz-crystal when value of ES/E6 daily difference Fig. units to cannot the NASA the into a daily 9C. course short-term In daily circuits. be each value the are of significant Time Since thus the be a is the a crystal. in practice, 6. assumed, was three continuous useful values the limit forming readily The clocks. of of second and obtainable clock, between the CLOCKS intercomparisons possible development be of of two providing Service It the one performance physical the approximately of Astrophysics 10 C6/E6 a sub-sequences, of re fully utilized fully will stability If of criterion are Tests month. performance, 19 possibility if -combination performed clocks. difference clocks accuracy deterioration two this to it microsecond. the The the however, the microseconds be is Cs plotted IS indication to with were from C6 causes, on clocks stabilities mean unnecessary information mean noted is and of of associate of ES the maintaining attained attained a short-term is Data indeed the of of by standards the II to parabolic C6 that in provides ancillary absolute absolute imposed and were that such relative since each further (in means of give of in clocks System Time for daily were The this per the the the the the the E6 by 77 by an of of of as to it a a 1953MNRAS.113...67S under the oscillation circuits indirectly circuit, of secondary filament stability equivalent, of precision control 325 conventional types. conventional maintaining drive-circuit, the fundamental amplitude. place replaced parallel, and the In crystal, of so The incorporating © the instability its the far In Reliability 5. associated cis 50 clock oven Royal first of superiority the cis Conclusions.-It crystal new particular, have than where oscillator have and would lamp. and without thyratrons, in divide mains heated of oscillator best may amplifier. Astronomical and experimental the amplifier been the The from a from was removal work in shown, the minor within of circuits, the conditions. result crystal often in crystal. As ambient the supply altering operation thermistor, controlling put as encouraging. which attention bridge which amplitude of a short incorporating circuits improvements, a has closer from however, first uses suff the of into This oscillator long-term is to both Society This either the oscillators the is changes been er now interruption has Greenwich obtain step, no operation a over gave limits ABINGER ampli was It greater control-temperature previously crystal amplifier, lower for for of transformers, cannot Humphry been nearly has designed valve that makes the • long directed oscillation the some standard, which a t by Provided ude-stabilized. and in these amplitude higher the was current CLOCK tungsten replaced in disturbance control a be FIG. ten in has periods fact Time of C6/E6 it E5/E6 factor it reason which current many achieved the employed. M. installed advantageous 1951 in refinements oscillation. 6. is years negligible to been standard COMPARISONS displaced by estimated is such as Smith heating Service. is bridge the of filament is by employs of cases controlled less the NASA the November. to these since is 50 possible, of oscillation. in by in reduction from a believe a supplied 000. than paramount the The way 1952 and circuit more the current of effect were The the the The employed Almost that to lamp conventional bridge-drive duplicated stability a 30 for crystal that oscillator Astrophysics control July. by quartz that pendulum directly failure achievement than thought on previous micro-amperes. by a which of the A was I was new mproved the In the a higher at importance, half second the heater Results battery-operated is from the clock, G T a the once derived of replaced valves frequency control by hard to not is valves a amplitude designs temperature temperatur clock most millidegree. be electrically a short-term Data crystals it -cut windings. oscillator, operating of design by tungsten valves obtained Vol. a may became from source higher circuit recent are in by virtue System since plate used The and II3 the an be of of of in in a e 1953MNRAS.113...67S apparent higher No. intercomparisons. stability which in experience inadequate instinctive of clock In and.it of found pendulum 9A extend battery note, run periods, Given established. standards performance the about may in compared mean even the 1950-1951 speed modern would day. month. Table which would of measuring The the © the the the those accuracy The Considering As monthly The I, since continuously Royal best has be however, technique have An absolute two 20'0. 1953 has Bulletin continuity that 1. and admittedly be can standard represent over regards operation past high with quartz observatories as that compared best the 1948 classed examination of It in Astronomical clocks reluctance been types with technique have and precision one subsequently modern the realization in several rates, valuable is these years the of It among pendulum short-term those available those It the Horaire. also that monthly installation clock January. of will claimed of first high-precision the the performance, been of of is a as as of since Greenwich there Quartz thus more control using the The good has have clock now years. possible with short-period fundamental in poor. power quartz aus deduced values be the investigation the property hitherto with has to only which the Paris of its giving a has of evident purpose Society clock forsake second advantages that complex quartz-controlled oscillator. quartz-controlled complex some stability them afforded average Mean been is the question criterion clocks made the of installation six years The a the supplies, Among Results rarely been only has otherwise clocks to criterion pendulum radio have Time to this corresponding other does a in unattainable. of made years the calculate pendulum daily numerical of the standards it been clocks that, • difference the the of the being standards, sta performance, of possible feature an Provided equalled not of time have not of of are the this superiority Service; pendulum since of b a relatively rewc ie Service, Time Greenwich the operation in rates since modified ility for unrivalled despite 8'5, length comparable quartz the one Greenwich in of yet the represent also quoted also at clocks capable the account signals, clocks, attained the period 1947 0' quartz the is Abinger criterion acquired failure whereas new and clocks problems are to now was I pendulum by by quality and sufficient mean clock figures millisecond of but carry recent Abinger But mentioned simple the NASA the quoted July, any clocks of in type of found far while Leroy of and uninterrupted of is that attainable, opportunity a clocks. Time at of a a up-to-date prolonged recent (18). serious it absolute uninterrupted to has for of of the national better other have out high the quartz of 9C a Paris the claims for is the concerning show a pendulum performance shows crystal the to for to clocks the clocks clock 1372, Ser·vice permitted other clock criterion perhaps since application quartz Astrophysics be not long-term justify years. quartz standard in pen per challenge each clocks During is facilities quartz clocks the to second this time ' milliseconds 3'4 uninterrupted combined were that published attained information d were comparisons oscillator. two run 1947 for day were ulum the month, further run, there the account, clock The in themselves clocks clock service. I t of run a a the clocks quartz a considerably a comparable have per for the contrary transferred which of new October, diff value to performance employed the is for of 50'0 retention clock. it gaining may is Data pendulum a reliability month the such worthy erences two frequency in and has advances is values regularly with standard standard accurate realm given at perhaps or may clocks. F1 of favour on typical firmly with easily Paris. runs, System these years been (1 long over ro'o The and and has per the per an 7 9), of in be of of to as in of of of 9 . a 1953MNRAS.113...67S 80 years docks resulting the this and selected clocks. selected undertaken long-term determined .()f in establishments value the in © the the Royal 1952 the 6 Time Post it opportunity . Royal that in .(14) Abinger (19) {II) (:r:S) (12 is were (13) (10) (:r:7) {:r:6) preparation (18) Acknowledgments.-The National (6) (5) (8) (3) (9) (4) (2) (7) (I) rotation October due the operation the Office ) Greenwich Dorking, en value mean Department, it H. W. H. H. H. A. N. W. L. L. Bulletin R. L. H. C. H. R. H. D. Astronomical performance first has in by to Forga, A. Essen, Danjon, B. F. L. M. M. M. H. B. M. Common, Stoyko, Spencer M. A. M. the the Quartz 9. introduced referring is Radio become Booth Turner, Meacham, Miller, Law, Physical of Marrison, Sadler, The Smith, Smith, of Smith, Smith, Smith, H. Surrey of Astronomique, regularly high Observatory, course l' Proc. expressing the Greaves the Astronomie, Annales Annales Journal Jones, various solutions various can and Experimental of under the Proc. clocks Proceedings M.N., British British Annales stability Journal possible I.E.E. : Earth. Society paper. that Phys. the the Laboratory. Bell of F. Bell be in M.N. and supplied I. Franfaises I.E.E., J. Franfaises normal National the astronomical of adopted the III, R. System Monograph, Science Science Soc., System various M. his I. tome Fra 65e E. the L. of to Information • , E.E Greenwich In direction 99, I.E.E., , 6 greatest Provided Laver, n appreciation the determine S. annee, Ref 24, 27, 94, 50, faises Greenwich . XV, and , current routine Technical 541, News, News, Technical T. to 81, de Time de present with 1951. erences investigations 446, Part 413, show 98, Synuns, Journal the fascicule de Chronometrie, Chronometrie, Development N 399, 112, 1939. of 2, observations 2, III, o 1939 advances 1938. Chronometrie, by Part confidence. Time . Service. a work relating Royal 207, 169, practice Journal, 39 Mr the 1951. 1937 J-Ournal, high clocks the NASA the T 38, . . of I.E.E II, M.N., ime 4, nature R. 1949. 1949. . Service 1947. by the 143, degree 291, Observatory H. 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