MI.M..H: XXIV.] THE ELECTHO-MOTIVE 1'OWKU OF HEAT. 



constant by uniting all the pairs intended to be worked 

 with at once. The current, therefore, whether general. -.1 

 by one, two, three, four, or more pairs, had always to run 

 through the same length of wire, and experienced in all 

 cases a uniform resistance. 



iM. By making each individual element of consider- 

 able length, the liability of transmission from the hot to 

 the cold extremity was diminished. 



Having, therefore, taken six pairs of copper and iron 

 wires, -fa of an inch thick and each element 38 inches 

 long, I formed them, by soldering their alternate ends, 

 into a continuous battery. Then I successively immersed 

 in boiling water one, two, three, etc., of the extremities, 

 their length allowing freedom of motion, and the other 



*^ O 



extremities not differing perceptibly from the temper- 

 ature of the room. 



The following table exhibits one of this series of ex- 

 periments : 



TABLE IV. 



Hence there cannot be any doubt that the quantities 

 of electricity evolved by compound batteries at the samt< 

 temperature are directly proportional to the number of 

 the pairs. 



With some general remarks, arising from the forego- 

 ing subjects, I shall conclude this Memoir. 



1. It is of importance to remember that thermo-electric 

 currents traverse metallic masses only on account of dif- 

 ferences of temperature existing at different points. 



