1863.] 157 [Coppee. 



" The problem of causing a clock to record its beats telegraphically, 

 was nothing more than to contrive some method whereby the clock 

 might be made (by the use of some portion of its own machinery) to 

 take the place of the finger of the living, intelligent operator, and 

 'make' or 'break' the electric circuit. The grand diflBculty did 

 not lie in causing the clock to play the part of an automaton in this 

 precise particular, but it did lie in causing the clock to act automati- 

 cally, and at the same time perform perfectly its great function of a 

 timekeeper. This became a matter of great difl&culty and delicacy ; 

 for to tax any portion of the clock machinery with a duty beyond the 

 ordinary and contemplated demands of the maker, seemed at once to 

 involve the machine in imperfect and irregular action. After due 

 reflection it was decided to apply to the pendulum for a minute 

 amount of power, whereby the making or breaking the electric cir- 

 cuit might be accomplished with the greatest chance of escaping any 

 injurious effects on the going of the clock. The principle which 

 guided in this selection was, that we ought to go to the prime mover 

 (which in this case was the clock weights, and which could not be 

 employed), and failing to reach the prime mover, we should select 

 the nearest piece of mechanism to it, which in the clock is the pen- 

 dulum. A second point early determined by experiment and reflec- 

 tion was this : that the making or breaking of the circuit must be 

 accomplished by the use of mercury, and not by a solid metallic 

 connection. Various methods were tried, and soon abandoned as 

 uncertain and irregular in their results, and the following plan was 

 adopted : 



" A small cross of delicate wire was mounted on a short axis of 

 the same material, passing through the point of union of the four' 

 arms constituting the cross. This axis was then placed horizontal 

 on a metallic support in Y's, where it might vibrate, provided the 

 top stem of the cross could be in some way attached to the pendulum 

 of the clock, and the ' cross ' should thus rise and fall at its outer 

 stem as the pendulum swings backward and forward. The metallic 

 frame bearing the ' cross ' also bore a small glass tube bent at right 

 augles. This was filled with mercury, and into one extremity one 

 wire from the pole of the battery was made to dip ; the other wire 

 was made fast by a binding screw to the metallic stand bearing the 

 'cross,' and thus every time the 'cross' dipped into the mercury 

 in the bent tube, the electricity passed through the metallic frame, 

 up the vertical standards bearing the axis of the cross, along the axis 

 to the stem, and down the stem into the mercury, and finally through 

 VOL. IX. — y 



