Ids 



from Greenwich. By means of electro-magnets and armatures, and a 

 peculiar arrangement for the transmission of a galvanic current once in 

 every twenty-four hours, this primary clock is also made to drop the 

 time-balls at Greenwich and at Charing Cross, and, when the arrange- 

 ments are complete, it will transmit signals for the regulation of the 

 large clock at the New Houses of Parliament. 



As an instance of the faciUty with which branch clocks may be 

 connected when once the main wire is laid down, the Astronomer Royal 

 told me, that when the main wire was carried through the Electric 

 Telegraph Office at London Bridge, on its road to the time-ball at 

 Charing Cross, a connection was made with the wire on its passage 

 through the office, without the knowledge of either the Astronomer 

 Royal or his assistants, and one of the secondary clocks was set to beat 

 simultaneously with the Greenwich clocks, and made to show exactly 

 the same time. The assistants at Greenwich, when they were acce- 

 lerating or retarding the primary clock, in order to make it show true 

 time, were therefore, without being aware of it, operating in a similar 

 manner on a clock five miles distant. 



There is an electric clock opposite the Electric Telegraph Office at 

 Charing Cross, and it has been stated, in the London newspapers, that 

 this clock is under the control of the sistronomers at Greenwich. Such, 

 however, is not the case. It is worked in the following manner. 

 There is a clock in the Electric Telegraph Office, which is put right by 

 hand, every day, when the time-ball drops, and this clock works the 

 clock in the street by galvanic currents. The street clock is erected on 

 the top of a lamp-post ; it has four faces, and the minute hand is made 

 to move on suddenly at the end of every minute. 



In a conversation wliich I recently had, on sympathetic clocks, with 

 Mr. Walker, the telegraph engineer on the South-eastern line, he 

 informed me tliat he had, at Tunbridge, a large clock going sympathetic- 

 ally at the distance of two miles ; its performance had been very 

 satisfactory during the two years that it had been going, and the battery 

 which worked the clock did not require attention more than once in 

 six months. 



From the experiments which have now been tried at Greenwich and 

 in London, there cannot be a doubt of the practicability of making one 

 primary clock work several secondary clocks at the distance of four or 

 five miles. Therefore, if one clock at the Observatory were made to 

 show correct time, as determined by astronomical observations from day 

 to day, other clocks, placed in different parts of the town, might be 

 connected with it, and all the clocks so connected would show precisely 

 the same time as the clock at the Observatory ; and if a time-ball were 



