FROM 1MF1 BRENT AI'IWKATI - | 



sisting of nine elbow joints : whereas, in apparatus No. 'i. eight 

 additional elbow joints, with sixteen and a half feet of straighl 

 pipe, amounting together to 28^ feet of pipe, were required to 

 save these five parts of the heat which would otherwise have 

 escaped into the chimney. The reason for this limitation will 

 appear evident, by reflecting that a heated body loses less in 

 equal periods of time, as its temperature approaches that of th< 

 surrounding refrigerating medium, and that the loss of heal 

 will be in the proportion which the volume of air in the pipe 

 bears to the volume of air in the room; and, afeo, proportional 

 to their ditference of temperature. 



It must not, however, be inferred from this experiment, that 

 13£ feet of pipe of any diameter, and thickness of iron, m 

 into elbow joints, will produce the same effect; as the length 

 will require to be increased with the increase in its diameter, 

 and this will appear obvious, from the fact, that the surface of 

 the pipe does not increase in the ratio of its ana ur contents 

 of heated air, and as this surface is the medium by which the 

 heat is imparted to the room, and that being effected princi- 

 pally by contact with the sides of the pipe greater length will 

 be required to produce this necessary contact. 



The great advantage of sheet iron stoves, is obvious, from 

 the slight obstruction which they present to the rapid commu- 

 nication of the heat generated, to the air of the room. 



From experiment No. 2, the advantage gained by lessening 

 the current of air into the chimney is clearly demonstrated; 

 this being the principal cause why this apparatus i< more effi- 

 cacious id warming the room than No. i ; and this advantage 

 does not arise so much from the excess of hea! which enters 

 the room by using Wo. 2. as from the diminished quantity of 

 cold air necessary to be admitted to supply tile place of the air 

 that /tits been heated, and of which, bv using No. I. the room 

 is constantly deprived in much larger volume than by N i. I 

 The advantage derived from using stove pipe of small diami I 

 arises from the same cause, and whether tie velocity of tl 

 current of heated air i< diminish) d l>y the construction, position, 

 or length of the pipe, or it- volume is diminish* d by n during 

 the diameter, the same effect is produced in every c 



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