produced by changes of' Temperature. 



309 



The numbers which express the deviations of the magnetis- 

 ed needle are the arithmetical means of the results of a great 

 number of experiments which it would be useless to detail at 

 present. With regard to the numbers which express the elec- 

 trical intensities we have given only the whole numbers. 



The following tables show the effect produced in a closed 

 circuit composed of two wires of copper and iron soldered at their 

 ends, and in which each joint is raised to a different temperature. 



Temp. 1st Joint. Temp. 2d Joint. Uev. of Needle. Electro-dynamic Intensity 



50° cent. 7°.15 11 



100 12 .75 22 



No. I. ISO 16 .00 31 



200 18 .00 37 



250 19 40 



300 



