44 SCIENCE Ltf SHORT CHAPTERS. 



of the fire by a " blower," or better still by selecting one of 

 the grates specially devised for burning anthracite, of which so 

 many now are made. Another and rather important matter is 

 to obtain the anthracite in suitable condition. It is a very hard 

 coal, too hard to be broken by the means usually at hand in 

 ordinary houses. For domestic purposes it should always be 

 delivered broken up of suitable size, from that of an egg to a 

 cocoa-nut. For furnaces, of course, large lumps are preferable. 



Then, again, anthracite must not be stirred and poked 

 about ; once fairly started it burns steadily and brightly, 

 demanding only a steady feeding. The best of the special 

 grates are more or less automatic in the matter of feeding, and 

 thus the trouble of lighting is fully compensated by the 

 absence of any further trouble. 



As regards the supply. This for London and the greater 

 part of England will doubtless be derived from the great coal- 

 field of South Wales. The total quantity of available coal in 

 this region, after deducting the waste in getting, was estimated 

 by the Government Commissioners at 32,456 millions of tons. 

 It is very difficult or impossible to correctly estimate the pro- 

 portion of anthracite in this, but supposing it to be one tenth 

 of true anthracite it gives us 3245 millions of tons, or about 

 enough for the domestic supply of the whole country during 

 100 years, assuming that it shall be used less wastefully than 

 we are now using bituminous coal, which would certainly be the 

 case. But, including the imperfect anthracite, the quantity 

 must be far larger than this, and we have to add the other 

 sources of anthracite. 



We need not, therefore, have any present fear of insufficient 

 supply ; probably before the 100 years are ended we shall find 

 other souces of anthracite, or even have become sufficiently 

 civilized to abolish altogether our present dirty devices, and to 

 adopt rational methods of warming and ventilating our houses. 

 When we do this any sort of coal may be used. 



