Chemistry and Physics. 391 
the objective of a telescope, this serves as L; if a flame or the like, it is 
placed at M near L, between L and T. 
The electric spark, when produced by the induction coil and allowed 
0 pass between the electrodes held at M, shows very interesting and in- 
structive phenomena; of which, however, it would be very difficult to 
give a clear idea in a few words. 
The sound-wave in air corresponding to each separate spark is, like 
of light. The spark from a Leyden jar gives a sharp sound, and one in- 
creasing circle of light one sound-wave, That this is a sound-wave, 
Topler proved by trying in vain to blow it aside by a feeble current of 
air, and also by finding it to progress more rapidly in heated air. But 
It may well be said that by means of Tépler’s apparatus we see the 
the specific gravity of gases, seems to contain any addition to our 
knowledge, st 
a 
* Theorie der Dampfmaschinen. Freiberg, 1861. 
