176 SECTION PHYSICS. 



existence of the oscillations of the current, but they cannot be con- 

 sidered very rapid. They occur at the rate of about 5000 a second. 

 In the vibrations of sound far higher figures than this are attained. 

 And thus the molecules might yet undergo vibrations. 



Now, all phenomena can be divided into two perfectly distinct 

 classes : into phenomena which propagate quickly and into those that 

 propagate slowly. To the first division belong light and radiating 

 heat, which are formed by the oscillations of ether, and which have a 

 propagating velocity of several hundred thousand kilometres a second. 

 Sound, communicated heat, &c., belong to the second class. They 

 attain a speed of some hundreds of metres, or, at the most, some kilo- 

 metres a second, and this speed is produced by the motion of the 

 molecules. The difference is immense between the first and the 

 second category. 



As to electricity, it propagates itself, in good conductors, at a rate 

 which can be compared to that of light. But the oscillations of the 

 current belong to the second division : they are slow. The conclusion 

 might be drawn that the motion of electricity in metals is caused by 

 ether or by another fluid of about the same elasticity and delicacy, 

 whilst in the oscillations of the current the molecules themselves 

 vibrate, or else they acquire in it a predominant influence. The oscil- 

 lations of the current are the result of a reaction of the helices on 

 themselves. They are phenomena of induction through bodies which 

 are bad conductors. They are consequently slow, and must not be 

 confounded with the vibrations, which the ether probably makes in 

 vibrating electrically in bodies, which are good conductors. They 

 stand in the same relation to these latter as the great waves of the sea 

 do to the small calorific vibrations, which the molecules of the sea can, 

 at the same time, produce. 



The CHAIRMAN : You have anticipated me by your applause in 

 asking you to pass a vote of thanks to Professor Blaserna for his most 

 interesting and lucid account of these most remarkable experiments. 

 In confirmation of what he has been stating, with respect to the 

 induced currents and the principal currents in an induction coil, I 

 may state that your President, in his way of experimenting, and I 

 and my colleague, Dr. W. H. Miiller, in ours, with a voltaic battery 

 consisting of several thousand cells, have come very much to the same 



