570 Of Chimney Fireplaces. 



ney fires, we must never forget that it is the room that 

 heats the air , and not the air that heats the room. 



The rays that are sent off from the burning fuel gen- 

 erate heat only when and where they are stopped or 

 absorbed; consequently they generate no heat in the air 

 in the room in passing through it, because they pass 

 through if, and are not stopped by it, but, striking against 

 the walls of the room, or against any solid body in the 

 room, these rays are there stopped and absorbed, and it is 

 there that the heat found in the room is generated. The 

 air in the room is afterwards heated by coming into con- 

 tact with these solid bodies. Many capital mistakes have 

 arisen from inattention to this most important fact. 



It is really astonishing how little attention is paid to 

 events which happen frequently, however interesting 

 they may be as objects of curious investigation, or 

 however they may be connected with the comforts and 

 enjoyments of life. Things near us, and which are 

 familiar to us, are seldom objects of our meditations. 

 How few persons are there who ever took the trouble to 

 bestow a thought on the subject in question, though it 

 is, in the highest degree, curious and interesting ! 



[This paper is printed from the English edition of Rumford's 

 Essays, Vol. III., pp. 387 400.] 



END OF VOL. II. 



Cambridge : Electrotyped and Printed by Welch, Bigelow, & Co. 



