AN ALL-PERVADING ELECTRIC ETHER. 25 



intervening between them, as is manifest by strik- 

 ing two stones together, by abrasion of steel by 

 a flint or emery-wheel, and by crushing pieces 

 of quartz, feldspar, and even dry lumps of sugar 

 in an iron mortar, whereby the interior appears 

 filled with electric sparks. 



Even the aeriform particles of the atmosphere 

 manifest similar electric excitation when mechani- 

 cally compressed beneath a piston in a small 

 cylinder, whereby tinder may be ignited; as was 

 often done before the invention of friction 

 matches. 



On beholding the bright flashes within a cleft 

 of dry wood suddenly laid open by his axe, a 

 pioneer in a Western forest once paused to ex- 

 press to the writer his belief that " fire exists in 

 wood, and comes out in burning." 



The ready permeation by the electric ether 

 even of non-conducting 

 glass, is shown by hold- 

 ing a plate of glass be- 

 tween an excited con- 

 ductor, A (Fig. 2), and 

 the knob of a conduct- 

 ing wire, B. As ex- 

 hibited in the drawing, every electric spark ap- 

 pears to pass instantaneously through the plate of 

 glass, as if it were perforated by it. 



This experiment illustrates the transmission 

 of electro-mechanical action through the electric 



