ST. JOHN. 



WAVE LENGTHS OF ELECTRICITY. 



231 



ute, and about 25 breaks were produced per second. The plunging 

 rods were thinned down at so tliat they were flexible and gave the 

 required freedom of motion ; they ran through the bed-plate and the 

 brass bar below, which served as guides. The plunging rods carried 



Fig. 6. 



lock-nuts by which the flexible coils leading the current from the 

 brass post Q were attached. The lower ends of the plungers were of 

 platinum wire, No. 18. The glass mercury cups had brass bottoms 

 that screwed into the brass arm N, which was adjustable by means of 

 the collar and binding screw L along the pillar P. At P was 

 attnched one pole of the battery actuating the coil, and also one pole 

 of tlie conden'ser in the base of the coil, and at Q was attached one 

 pole of the coil and the other pole of the condenser. 



