284 0. T. Knipp — New Form of Make and Break. 



ment is readily effected by means of the thumb and the set- 

 screws. Two binding posts are conveniently placed to which 

 the circuit from the battery and sounder is connected. Obvi- 

 ously the circuit is closed only when the pendulum passes 

 through its lowest point — when the platinum tips are in con- 

 tact with the two springs. Fig. 1 shows the pendulum at the 

 extreme end of its path. The right-hand spring is depressed 

 while the left-hand platinum tip is a considerable distance 

 above its spring. A small piece of platinum foil is soldered to 

 the spring just below the platinum tips to insure good elec- 

 trical contact. The friction is very slight. The pendulum, as a 

 consequence, will have a smaller amplitude, causing the clock 

 to run some faster. The friction at the points of contact of 

 the platinum tips can be greatly reduced by shortening the 

 arms of the T, thus making the springs and arms of equal 

 length and approximately radii of the same circle. Fig. 2 is a 

 side view showing the stud on the pendulum, the pivot, and 

 support. 



The writer made this device and placed it in position March, 

 '97. After being once adjusted it gave no trouble. Wires were 

 run to the various laboratory rooms. The device is always ready 

 and responds promptly when the sounder is attached. 



Physical Laboratory, Indiana University, 

 Bloomington, Ind. 





