28 Of the Management of Fire 



used for a length of time in the same culinary processes ; 

 and the quantity of fuel consumed by each being noted, 

 the comparative advantages of their different forms were 

 ascertained. Some of these boilers were made deep and 

 narrow, others wide and shallow ; there were some with 

 flat bottoms, others of a globular form, and others again 

 with their bottoms drawn inward like the bottom of 

 a common glass bottle. The results of these inquiries 

 were very curious, and led me to a most interesting dis- 

 covejy. They taught me not only what forms are 

 best for boilers, but also (what is still more interesting) 

 why one form is preferable to another. They gave me 

 much new light with respect to the manner in which 

 flame and hot vapour part with their heat ; and sug- 

 gested to me the idea of a very important improvement 

 in the internal construction of fire-places, which I have 

 since put in practice with great success. 



But in order to be able to explain this matter in a 

 clear and satisfactory manner, and to render it easier to 

 be understood by those who have not been much con- 

 versant in inquiries of this kind, it will be necessary to 

 go back a little, and to treat the subject under consid- 

 eration in a more regular and scientific manner. 



Though it was not my intention originally to write an 

 elementary treatise on heat, yet, as the first or funda- 

 mental principles of that science are necessary to be 

 known, in order to establish upon solid grounds the 

 practical rules and directions relative to the manage- 

 ment of heat which will hereafter be recommended, it 

 will not, I trust, be deemed either improper or superflu- 

 ous to take a more extensive view of the subject, and 

 to treat it methodically, and at some length. 



I have perhaps already exposed myself to criticism by 



