VOLTAIC GENERATORS. 37 



assimilation of the mode of propagation of electricity to that 

 of heat as propounded by Ohm, and on account of the posi- 

 tion they thus assumed they arrived at such discordant 

 results regarding the velocity of electrical propagation, that 

 they were obliged to admit that either the experiments made 

 for the measurement of that velocity had been badly con- 

 ducted, or that the commonly accepted ideas on the propa- 

 gation of electricity were false. 



About the year 1859, Gaugain, a skilful physicist, who had 

 for some time been engaged in verifying Ohm's laws as 

 regards the transmission through badly conducting bodies, 

 investigated the causes of this discordance, and soon found 

 the solution of the enigma. He ascertained that electricity, 

 so far from being propagated like light with a constant initial 

 intensity in every part of its course, must, on the contrary, 

 as Ohm had found, be transmitted in the same manner as 

 heat is propagated in a bar of metal heated at one end and 

 maintained at a lower constant temperature at the other end. 

 In this case the heat is communicated from particle to particle 

 beginning at the heated end of the bar, and in proportion as 

 the calorific movement is propagated towards the other end, 

 the parts first heated acquire a greater and greater quantity of 

 heat, until when the calorific movement has reached the cold 

 end, the different points of the bar lose as much heat on the 

 one side as they gain on the other. Only then is the calorific 

 equilibrium established, and the distribution of heat in all 

 parts of the bar remains constantly the same. This is the 

 condition called by physicists the permanent calorific state. 

 But before a metallic bar arrives at this condition, there must 

 elapse an interval of time, longer or shorter, according to the 

 calorific conductivity of the bar, during which time each point 

 of the heated body is continuously changing its temperature. 

 If the assimilation of the propagation of heat to the propaga- 

 tion of electricity be correct, a like variable period must exist 

 during the first moments of the propagation of a current. 

 According to this hypothesis an electric current is, in fact, 



