298 FKOM NEBULA .TO NEBULA 



earth-body being made warm by compression, threaten- 

 ing the destruction of our planet by the accumulation of 

 central fires ; and, on the other, an automatic cooling de- 

 vice for conveying this surplus warmth up through the 

 sea in its passage serving its own good purpose in 

 tempering the water to the needs of the living creatures 

 that inhabit it. Indeed, were it not for this immense ad- 

 ditional source of heat supplied by Mother Earth her- 

 self, the oceans would long ago have f rozn to a great 

 depth (not solid to the bottom, however, for the reasons 

 shown), and not only would all existing life never have 

 come into being, but it is more than doubtful whether any 

 life whatsoever could have got a start. 



From time to time the suggestion is revived to sink a 

 well two or three miles deep for the purpose of tapping 

 the earth's store of internal heat; but nothing has come 

 of it as yet, so far as I am aware. That such a project, 

 if carried out in earnest, would bring with it many sur- 

 prises, perhaps not all of an agreeable character, is 

 scarcely to be doubted. However, there is an alternative 

 method which to my mind is much more feasible. This 

 is to construct presses of suitable materials capable of 

 bringing to bear the highest possible leverage on, say, a 

 body of lead or iron, imbedded in which should be a coil 

 of pipe made of some stout, refractory material, through 

 which water might be kept circulating. Under these con- 

 ditions the pressure-liquefied metal would continuously 

 preserve a high temperature and steam would be gen- 

 erated without interruption, according with the capacity 

 of the machine. Just how much pressure would be re- 

 quired in a given case can be estimated in this way: 



The pressure of the atmosphere at sea-level will sup- 

 port a column of water 34 feet high, and this pressure is 

 equivalent to 15 pounds to the square inch. If now we 

 assume, what is approximately true, that the material of 

 the earth's crust is three times as heavy as water, and 

 that the temperature of the crust increases at the rate of 

 one degree in every 68 feet (2 x 34) we find that to raise a 

 given substance one degree we must apply a pressure of 



