98 Mr. W. Sturgeon on Electro-Magnetism. 



erted in the same direction ; for the wires are of the same 

 kind, and are propelled the same way. 



The conclusion still holds good, when the junction of the 

 wires is heated at D instead of E. 



Having thus ascertained, by the former supposition, that 

 the forces of the chemico and thermo galvanized wires are 

 exerted in contrary directions, and that by the latter supposi- 

 tion these forces are exerted in the same direction; I shall 

 leave the theorizing philosopher to adopt which side of this 

 dilemma he may think fit; for it is not my province to pre- 

 dict whether we are to have a thermo-electric force acting in 

 a contrary direction to our old galvanic force, by the former 

 supposition, or whether we are to have these two forces re- 

 conciled to each other by the latter ; — my business being only 

 to ascertain some general law, whereby to regulate my sub- 

 sequent experiments. 



I have since made experiments, both chemico and thermo, 

 with combinations of other metals ; and the results have given 

 me the greatest satisfaction that the above law is general ; 

 for the comparison is, in all that I have made, the same as 

 with copper and zinc. 



Here follows a description of the instrument I have made 

 for the purpose of exhibiting and comparing chemico and 

 thermo phenomena as influenced by the magnet ; by means of 

 which I can make the experiments with the greatest facility and 

 exactness. I have named it the Comparing Galvanoscope. 



Fig. 1. A cylindrical glass tube supported by the arm Cc 



of 



