308 M. Becquerel on the Electric effects of Contact 



points of the circuit heated by the mercurial bath attain ex- 

 actly the same temperature at the moment of observation. 

 This may be obtained by raising the temperature to the heat 

 at which the experiment is to be made, and suddenly extin- 

 guishing the lamp. The temperature will then remain sta- 

 tionary for some seconds, and we are certain that the thermo- 

 meter and the soldered joints have the same temperature. 



The following table contains the results of the experiments 

 thus made. 



It appears from this table, that from 0° to 10° of deviation 

 the increments of heat are proportional to the increments of 

 deviation, but beyond that term the ratio is no longer the same. 



Let us suppose, however, that the deviation 1°.30 is produ- 

 ced by an electro-dynamic force equal to 2, the deviation 2.60 

 will be produced by a force equal to 4, because there are two 

 wires in action ; the deviation 3.90 by a force equal to 6, &c. 

 By continuing the same reasoning, and by placing beside each 

 deviation the number which corresponds to it, and admitting, 

 that, at the same temperature, two wires produce a double 

 force, three a triple force, &c. we shall form the following 

 table, in which we have, in one column, the deviations of the 

 magnetic needle, and in the next the corresponding intensities 

 of the electro-dynamic force. 



