318 HISTORY OF ASTRONOMY. 



the motion of the pendulum; the lever to turn on a 

 center near the point of suspension, but insulated 

 from it. 



In 1849, the arrangement with a glass pin moving a 

 platinum tOt-hammer was applied by Mr. Saxton to the 

 Hardy clock of the Coast Survey, and put in operation at 

 the Seaton station in July of that year. This arrange- 

 ment is shown in the annexed cut. ABC represents a 



fine platinum wire, mounted on a pivot at B, the end A 

 being somewhat heavier than the other, and resting upon 

 a metalic bed D. At C the wire is bent so as to form an 

 obtuse angle. The wire E goes from D to one pole of 

 the battery, while the wire H from the other pole of the 

 battery, communicates with the metallic support Gr, and 

 thence with the wire A B. When the -end A of the 

 platinum wire rests upon the support D, it is evident that 

 the electric circuit is complete. This apparatus is placed 

 near the middle of the pendulum (a portion of which, 

 I K, is represented in the cut), and just in front of it, so 

 that the pendulum may swing behind it without obstruc- 

 tion. A small glass pin F, about half an inch in length, 



