22 



Now let us place this copper bar flat across the- couple 

 21); the galvanometer falls to 3. If it had 



soldered it would have indicated zero, but some small air 

 - arc between, and some few of the ZA cogs arc 

 noving, or in the ascendency. Of course the main 

 of this alteration is the change of the position of the 

 copper bar, which in the second case allows the Iron 

 molecules to be almost the same temperature as the X \ 

 molecules, and which, therefore, is acting as a drag, /.<., pre- 

 venting the ZA molecular cogs from doing work upon the 

 Iron molecular cogs. Fig. 7 shows the same cause at work 

 in a modified form. 



The galvanometer shows (Tig. 4), at 375 F., that the ZA 

 molecular cogs have the most power ; but when the couple 

 is plunged, at this temperature, into the pot of melted wax, 

 all molecules, both ZA and Iron, arc brought to the same 

 c of heat, therefore no molecular stress, ZA against 

 Iron or Iron against ZA, i >lc ; the two sets of 



