February i6, 191 i] 



NATURE 



517 



the main wires being temporarily connected to the 

 subscribers' circuits by a switch. The Greenwich 

 signal is transmitted to the Central Telegraph Office 

 every hour, and it is therefore available for the use of 

 such persons in London as require it, some few of 

 whom exist. 



For the temporary connection of the wires converg- 

 ing on London, which are normally associated with 

 telegraph apparatus, to the Greenwich wire, a unique 

 automatic switching device, called the Chronopher, 

 is in use, a portion of which has existed since the 

 early days of the telegraph companies. The apparatus 

 consists of a multiple switch the movements of which 

 are governed by a clock which, by means of certain 

 electrical contacts, is arranged to operate the switch 

 at the proper time. The clock itself is automatically 

 corrected or synchronised by the Greenwich signal, 

 and this clock, which seems to be coeval with the 

 Chronopher, in common with certain others of a 

 similar type, is probably one of the earliest successful 

 endeavours to achieve automatic synchronisation, by a 

 svstem which seems to have been introduced by ^Ir. 

 C V. Walker, of the Electric Telegraph Company. 

 .About 1876 Ritchie, of Edinburgh, introduced an 

 improvement on a synchronising system (as distin- 

 guished from a sympathetic system), invented by Bain 

 in 1842, and later appears to have improved on 

 Walker's system, and many clocks synchronised on 

 this principle, as well as Walker's, one of which is 

 yet used at Aldershot for military purposes, are be- 

 lieved to be still in use. 



There appear to have been one or two other syn- 

 chronising methods introduced during the past few 

 decades, but with the exception of the Standard Time 

 Company, the operations of which are confined to 

 London, and a system invented by Mr. Lund, none 

 seems to have achieved a large measure of success ; in 

 fact, the Greenwich time signal transmitted by the Post 

 Office is, in general, used to drop time ball, fire guns, 

 or to give other visible or audible signals, the correc- 

 tion of clocks being performed by means of human 

 intervention. A noteworthv method for accomplish- 

 ing the latter is that introduced by Sir George Airy, 

 sometime .Astronomer Royal, which is still used by 

 the Admiralty for correcting;^ the standard clocks at 

 their various dockvards. Each clock, in addition to 

 its ordinary compensated seconds-beating pendulum, 

 is provided with an auxiliary free pendulum, arranged 

 to swing behind the clock pendulum. Normally the 

 latter is latched to one side on a trigger which, at the 

 proper time, is released by the Greenwich signal. 

 "\Vhen both pendulums are swinging, observations 

 are made to ascertain the phase relationship, and a 

 current of electricity is passed through a fixed elec- 

 tromagnet in such direction as to attract or repel the 

 poles of a permanent magnet attached to the clock 

 pendulum, thereby accelerating or retarding the latter 

 until both pendulums are swinging in synchronism. 

 The British Science Guild Committee, however, 

 mentions that the correction of clocks by hand is 

 quite out of date and untrustworthy, and is unani- 

 mously of opinion that some form of direct physical 

 control of public clocks by electrical synchronisation 

 signals from a central time authority is essential. 

 It seems strange that in a city like London, the 

 largest in the world, and the most important com- 

 mercially, where exact timekeeping would seem to 

 be of the utmost importance, there should be so few- 

 clocks really to be relied upon. The committee refers 

 to "Big Ben," which automatically reports its time- 

 keeping performance to Greenwich Observatory, and 

 the larg-e clock in the portico of the old Post Office 

 in St. Martin 's-le-Grand, which is already electrically 

 synchronised, as being probably the two large public 



NO. 2155, VOL. 85] 



clocks in London which can best be relied upon to 

 indicate Greenwich time. 



The committee has approached the London County 

 Council, the City Corporation, H.NL Office of Works, 

 the Local Government Board, the Post Office, and the 

 various railway companies, but the response to its 

 inquiries seems to be very discouraging. It appears 

 that the question is treated rather apathetically by 

 all save the Post Office authorities, who alone appear 

 to realise the immense importance of the matter, and 

 who have, within recent years, adopted a simple 

 system applicable for the correction of large and 

 small clocks, as well as public turret clocks, and 

 who are extending the system as circumstances 

 permit. It is stated that the cost of synchronising 

 apparatus is small for any size or type of clock, 

 so that it is possible that one of the main objec- 

 tions to the use of the Greenwich time signal, as 

 at present transmitted, is the amount of the sub- 

 scription to the Post Office which it involves. It is 

 tj be hoped therefore that, if the synchronisation of 

 clocks is to be effected to any considerable extent, 

 the authorities will see their way to provide a syn- 

 chronising signal at a rate which will not appear to 

 be prohibitive to those who have public clocks under 

 their control. 



It is clear from other reports which have appeared 

 from time to time in the Press that municipal authori- 

 ties and the public are not quite so apathetic as it 

 might appear at first sight, for recently, public clocks 

 have been installed by the local authorities at Aber- 

 deen and Sheffield, and are about to be erected at 

 Liverpool and at Taunton, which are, or will be, all 

 electrically synchronised to Greenwich time. The fact 

 that most of the makers of electric clocks, too, arrange 

 for their master or controlling clocks t(> be syn- 

 chronised as required, seems to indicate that they 

 appreciate the feeling that there is some public 

 demand in this direction. 



The committee makes a comparison between the 

 practice in this country and the practice abroad, where 

 the importance of correct time seems to be more fullv 

 appreciated than here ; but, no doubt, although pro- 

 gress in the matter has been somewhat slow in the 

 past, given a reasonably cheap synchronising service, 

 London and the rest of the country will ere long 

 awake to the fact that, as the committee expresses 

 it, a meretricious clock is equally as dangerous as a 

 false yard measure, and then the observance of abso- 

 lute time, once fairly started in operation, will be a 

 recognised factor in our daily existence. 



JULIUS WILHELM BRUHL. 



IT is with much regret that we have to record the 

 death at Heidelberg, on February 5, of Prof. 

 Briihl, the distinguished chemist. He was of Jewish 

 parentage, and was born at Warsaw in February, 

 1850, and studied from 1868 to 1873 at Zurich and 

 Berlin. In 1873, on completion of his studentship, he 

 became assistant to Prof. Landolt at Aachen, and in 

 1879 was appointed professor in the University of 

 Lemberg, which chair he resigned in 1884 on account 

 ot ill-health brought on by the unsuitability of the 

 climate. After some sojourn at Freiburg (in Breisgau) 

 he was induced by Bunsen to transfer his services to 

 Heidelberg, where, in 1887, he became honorary pro- 

 fessor in the high school, and took over the private 

 laboratory of Prof. Bernthsen, who had then entered 

 the service of the Badische Anilin und Soda-Fabrik at 

 Ludwigshafen. In 1889 he commenced lecturing as 

 Bunsen 's representative, and was giv^en full title as 

 honorary professor in 1908. Briihl's contributions to 

 science will be appraised in due course : they are 



