THE FORCE OF DYNAMITE ALWAYS DOWNWARD 193 



were no visible effects above the charge (as, indeed, how 

 could there be?) the theory was believed to have been 

 proved beyond doubt. 



But every engineer and miner knows that if the slab of 

 stone were raised from the ground and supported on 

 pillars, the dynamite if placed under it would shatter it as 

 effectually as if it were laid on the top of it. The truth is 

 that the expansive force of dynamite has no tendency to 

 act in any one direction rather than in another. Numer- 

 ous experiments prove this beyond any question. 



The explanation of the apparent downward action of 

 dynamite is quite simple. The destructive power of dyna- 

 mite and similar explosives is due to the tremendous rapid- 

 ity with which the resulting gases expand in every direction 

 when exploded; indeed so rapid is this explosive action 

 that neither solid nor aerial matter can get out of its way 

 fast enough. Black gunpowder when burned on a stone 

 slab (unless the quantity be very large) simply gives a 

 slow puff and passes off in smoke. A little of it burned 

 on the palm of the hand burns so slowly that it will scorch 

 the flesh. But if we place a little fulminating mercury on "^ 

 the palm of the hand and touch it with a spark of fire it / 

 goes off with a sharp puff and burns so rapidly that there ( 

 is no time for it to impart a perceptible amount of heat to-^ 

 the hand. It may even be burned on a pile of common 

 black gunpowder without setting the latter on fire. If, 

 however, we should select a still more rapidly expansive 

 explosive, such as dynamite, and set that off on the hand, 

 the hand would probably be torn to shreds. 



Even when there is no solid material placed over the 

 dynamite to concentrate the action of the expanding gases, 

 there is always present the enormous pressure of the atmos- 



