FORCE OF THE WESTON NORMAL CELL IN SEMI-ABSOLUTE VOLTS. 
163 
(vi) The current is reversed back to the original direction and the galvanometer 
reading at 90 seconds is noted. 
(vii) The Kelvin-Varley slide is reversed (i.e., the terminals are interchanged) and 
FIG. 4 
the new reading and accompanying galvanometer deflection are noted at 210 # seconds 
after the change. 
(viii) The current is reversed, and the galvanometer read at 240* seconds. 
* These intervals were decreased when 
attained. 
proficiency in performing the operations rapidly had been 
Y 2 
