430 



NATURE S TEACHINGS. 



The pail, rope, and winch which were in use at that time 

 and may be still, to the sorrow of the gardener are but a 

 sort of semi-savage way of procuring water from the depths of 

 the earth. It is a well-known fact that under certain condi- 

 tions water always finds its own level) minus the friction of the 



channel through which it passes. On this principle all foun- 

 tains are made. Those, for example, at the Crystal Palace, 

 which fling their waters to such a height, are fed from tanks 

 on the summit of the two great water towers. And, were it 

 not for the friction of the water in the tubes, and that of the 

 air, the fountains would rise as high as the tanks from which 

 they are fed. 



Such is the case with springs, especially with those of an 

 intermittent character, in which latter instance the rushing of 

 the water is exactly coincident with the filling of the hidden 

 tank which supplies it. 



The modern Hydrant system, which bids fair to supersede 

 the cumbrous machinery of fire-engines, even when worked by 

 steam, is based on the same principle. The water-tanks are 

 placed at such a height that, when a hose is attached, and the 

 tap turned, the water can be thrown over the roof of the 

 highest building. Such hydrants have been attached to Can- 

 terbury Cathedral since the fire which so nearly consumed that 

 magnificent and venerable building. 



A VERY remarkable use has been made of this power of 

 water in mining operations. Most of my readers know that in 

 gold mines the metal is chiefly found scattered among quartz, 

 one of the hardest of the minerals. The usual plan has been 

 to dig out the quartz, pound it to powder with specially 



