163 



Length of solenoid, 9.5 cm. Number of turns, first coil 176, second coil 

 273. The force of the sjiring rei)resonted l^y one turn of the micrometer screw 

 is 13 grams or 0.028 lb. 



Record for a Cold Rolled Steel Rod U.5 in. Dluin. Coil 176 Turns. 



