346 Means of increasing the Quantities of Heat 



they throw off into the room incomparably more heat 

 than all the coals that could possibly be put into the 

 grate, even supposing them to burn with the greatest 

 possible degree of brightness. Hence it appears that a 

 red-hot burning coal does not send off near so many 

 calorific rays as a piece of red-hot brick or stone of the 

 same form and dimensions ; and this interesting dis- 

 covery will enable us to make very important improve- 

 ments in the construction of our fireplaces, and also in 

 the management of our fires. 



The fuel, instead of being employed to heat the room 

 directly or by the direct rays from the fire, should be so 

 disposed or placed as to heat the back and sides of the 

 grate, which must always be constructed of firebrick 

 or firestone, and never of iron or of any other metal. 

 Few coals, therefore, when properly placed, make a 

 much better fire than a larger quantity, and shallow 

 grates, when they are constructed of proper materials, 

 throw more heat into a room, and with a much less 

 consumption of fuel, than deep grates ; for a large mass 

 of coals in the grate arrests the rays which proceed from 

 the back and sides of the grate, and prevents their com- 

 ing into the room ; or, as fires are generally managed, 

 it prevents the back and sides of the grate from ever 

 being sufficiently heated to assist much in heating the 

 room, even though they be constructed of good materi- 

 als and large quantities of coals be consumed in them. 



It is possible, however, by a simple contrivance, to 

 make a good and an economical fire in almost any grate, 

 though it would always be advisable to construct fire- 

 places on good principles, or to improve them by 

 judicious alterations, rather than to depend on the use 

 of additional inventions for correcting their defects. 



