9ik 



doubtedly purer and more wholesome for drinking purposes than 

 the always more or less contaminated waters of surface springs, 

 rivers or lakes. 



"We bear a good deal about our coal supplies becoming exhausted, 

 so it is consoling to hear from America that the coalfields of that 

 country alone are sufficient to supply the whole world for some 

 2000 years longer. No doubt the apparently inexhaustible supplies 

 of petroleum recently discovered in Eussia, and which are brought 

 through wooden pipes some 500 miles to the seaboard, will furnish 

 a cheap substitute for solid fuel in the immediate future. Petroleum 

 has been recently used, not only for smelting operations, but as a 

 substitute for steam in propelling vessels. These ships have 

 neither paddle-wheels nor screw, but carry a large tank containing 

 petroleum, which is conducted in small charges along a steel pipe 

 which opens in the stern of the vessel just below the water-mark. 

 It is here mixed with atmospheric air to render it explosive, and 

 each charge is fired in quick succession by electricity. The force 

 of the explosion being expended on the water astern is sufficient 

 to propel the vessel at the required speed. A practical step in the 

 direction of utilising the internal heat of the earth has been made 

 at Pesth, where a well has been sunk to 3,000 or 4,000 feet in 

 depth and water raised at 180 degrees of heat, a temperature at 

 which most culinary operations can be conducted. I have myself 

 cooked food in water thus heated at the geysers, the celebrated 

 boiling springs in Iceland. Whether this means of obtaining heat 

 would pay is extremely doubtful ; it would be a question of the 

 relative expense of very deep boring or raising of coal. As the 

 thickness of the earth's solid crust is variously estimated at from 10 

 to 400 miles, it would in no case be a very easy engineering task to 

 tap the intensely hot fluid matter of the earth's interior, or even to 

 reach a depth at which we might theoretically expect to find a 

 temperature of 212 degrees. The interesting experiments lately 

 made by M. Spring, of Liege, seem to prove that all matter 

 becomes fluid under extreme pressure, even metals flowing like 

 water under a pressure of 750 atmospheres. These facts seem to 

 settle the vexed question as to the solid or fluid condition of the 

 earth's centre, since, if the hardest metals become fluid at a pres- 

 sure of 700 or 800 atmospheres, which would obtain at a depth of 

 12 miles below the surface, no imaginable rock could remain 

 solid at the inconceivable pressure which much exist at 2,000 miles 

 of depth. 



They are making great progress with the celebrated Lick Obser- 

 vatory in California. The great telescope, with the large 3ft. 

 refractor, is at last finished, having cost £100,000. It is now 

 proposed to provide a wonderful automatic apparatus. " On enter- 



