PREFA CE. Vll 



from the Scientific American Supplement ; and one from 

 Engineering News. 



The work .has been unavoidably delayed waiting for de- 

 sired data, some of which came too late to be used. 



The author knows well that the book is far from perfect 

 or complete, but it is as near so as could be made with the 

 diverse kinds of material obtainable. Some errors, especially 

 in the tables, may be found, which he hopes to correct in the 

 future. 



That it may be found of service and aid to others in their 

 work on fuels is the sincere wish of the author. 



HERMAN POOLE. 

 NEW YORK, Jan. i, 1898. 



