SENSITIVE FLAMES, ETC. 189 



this white screen. Now I strike this first fork, and the 

 vibration will be transmitted through the air to the other 

 fork, against which a bead is placed. You will find 

 that the second fork is thrown into motion by the motion 

 of the first fork. This is remarkable, inasmuch as we have 

 the transference of motion through the air to this very 

 heavy massive fork. If, however, I attach to one fork a 

 little wax it will be thrown out of tune, and I shall not 

 be able to obtain this response, for it now vibrates at a rate 

 slightly slower than before, and we shall find that it will 

 not affect the other fork. There is no trace of vibration. 



These are illustrations of the acceptance of vibrations 

 by gross matter. 



The same law holds true, as you are aware, with regard 

 to the finer matter composing the ether. If I move this 

 magnet to and fro, it is capable of setting the little magnet 

 below it also in motion to and fro, and this action takes 

 place although I may have one of the magnets in a 

 vacuum, so that it is very evident that the vibration of 

 the magnet is not communicated to the other magnet by 

 means of gross matter. It is communicated by means of 

 something which is finer than the matter which we can 

 weigh the insensible matter which we denominate ether. 



A more striking and beautiful illustration of this fact is 

 given in the following experiment. In front of a soft iron 

 rod surrounded by a coil of wire, a bar electro-magnet, in 

 fact, a magnetized tuning-fork, is firmly fixed. Wires 

 lead from the coil to a second similar arrangement at a 

 distance. On now bowing the first fork, which is mounted 

 on a non-resonant surface, the distant fork, mounted on a 

 resonant box, is heard to sound. The two forks are exactly 

 in tune, and the approach and recession of the magnetized 

 prong to the coil of wire generates electric waves, which 

 are converted into magnetic pulsations in the second fork, 

 the rhythmic rise and fall of which throw it into corre- 

 sponding vibration. But if one of the forks be loaded the 

 response ceases, for there is no longer synchronism through- 

 out the system. 



In like manner heated bodies emit vibrations which 

 are accepted by other bodies if the rates of vibration of 

 the cool substance coincide with the rates of vibration in 

 the hot ones. This fact was pointed out long since by 



