330 



BENJ. PIKE S, JR., DESCRIPTIVE CATALOGUE. 



single large pairs is greater, but its intensity less than that 

 given out by an equal quantity of metallic surface arranged 

 in several successive pairs. Price, $25 to $40. 



Wollastorfs Battery. Tig. 3^3. 



(Figs. 388 & 389.) 

 A great improvement 

 in the construction of 

 galvanic batteries was 

 made by Dr. Wollaston 

 in 1815. This improve- 

 ment consists in extend- 

 ing the copperplate so 

 as to oppose it to every 

 surface of the zinc, as 

 represented in the cuts. 

 A is the rod of wood to 

 which the plates are screwed in the usual manner ; B, B, 

 the zinc plates connected as usual with the copper plates, 

 c, c, which are doubled over the zinc plates, and opposed 

 to them on both sides, any contact with the surfaces being 

 prevented by pieces of cork or wood placed between. 



Fig. 339. 



This construction of the galvanic battery is no more used, 

 by reason of the superiority of the new instruments. 



Price, 50 pairs, $50.00. 



