Methods for Observing A tmosphsric Electricity. 



277 



may be made by its aid, to ascertain the absolute value and the con- 

 stancy of the water cells. The difficulty thus met is altogether done 



Fig. 1. — Water Appanitiu 



1 i^ 2.— Divided King Klectromcler. Y\g- 3. — Portable Atmosjiheric Electrometer. 



away with in another kind of ek'i;tro;Tieter, also " heterostatic," of 

 which only one lias yet been constructed — the electrometer of 



