June I, 1876] 



NA TURE 



II I 



travels (about four miles in nineteen seconds). Time- 

 guns are thus automatically discharged at i p.m. daily at 

 Newcastle, Sunderland, Middlesboro', and Kendal. 



The action of the apparatus, both at Greenwich and 

 in the Post Office, is entirely automatic. Still, in the 

 extension of the system, inquiries have sometimes been 

 made as to the degree of exactness of signals received 

 through the chronopher ; the accuracy of its transmission 

 has therefore been tested by direct experiment. One of 

 its distributing wires was connected to a wire returning 

 to Greenwich, so that the current leaving the Royal Ob- 

 servatory to act on the chronopher could be directly 

 compared with that received at Greenwich from the chro- 

 nopher. The currents were'made to pass through galva- 



nometers placed side by side, but there was no sensible 

 difference in their indications. It follows, therefore, that 

 entire confidence can be placed in the distribution by the 

 chronopher. 



As showing the extent to which demand for the auto- 

 matic chronopher signals has increased, it may be men- 

 tioned that for some years past the British Postal Guiae 

 has contained a tariff of annual charges for which the 

 telegraph department will supply such signals and main- 

 tain the special connecting wires, both in London and the 

 country. 



The automatically transmitted signals are scientifically 

 accurate, but a very extensive practical distribution of 

 time is also made daily at 10 A.M. by hand ^contact. In 



Fig. 2.— New Ghronopher (or time distributing apparatus in the Central Postal Telegraph Office, St. Martins-le-Grand. 



the large instrument room of the central telegraph station 

 a " sound " signal is established in connection with the 

 chronopher. When heard at 10 a.m., the clerks, being in 

 readiness, ipimediately transmit signals by their ordinary 

 speaking instruments to above 600 offices in direct com- 

 munication with the central station, including those in 

 towns not supplied from the chronopher, the London 

 offices, and the principal London railway termini. At 

 many of these offices the signal is redistributed to others 

 radiating from them, and so practically regulates most of 

 the post-office and railway clocks of the country — these 

 in their turn, insensibly as it were, regulating the clocks 

 of the surrounding districts. 



Thus, either by the accurate chronopher signal, or by 



the arrangement spoken of in the preceding paragraph, 

 the loh. current each morning from Greenwich, through 

 the Post Office telegraph system, gives time simul- 

 taneously in all parts of the United Kingdom. 



One of the chronopher lines in London passes to the 

 clock-tower of the Westminster Palace, and hourly signals 

 are received at the clock for its necessary rating and 

 adjustment. It is, however, in no way controlled or 

 mechanically acted upon by the time currents. Prac- 

 tically, the clock requires to be very rarely touched ; if 

 change becomes necessary, it is usually made by adding 

 to or removing from the pendulum small auxiliary 

 weights. The clock also completes a galvanic circuit at 

 a certain time daily, and so transmitting a signal, reports 



