70 Transactions of the American Institute. 



tions of the former were so accurate that it was made the standard 

 during the trial, and the latter, also remarkably accurate, by its- 

 record of time, as well as pressure, was a most valuable check upon 

 the record of the log as obtained by observations at regular intervals-. 



The quantity of water passing through each boiler was determined 

 by weighing it, 300 pounds at a time, on carefully adjusted scales. 



The Superintendent of Machinery and his assistant, Messrs. J. W. 

 Blake and J. B. Fitch, who, representing the Committee, had imme- 

 diate charge of the trials, were aided, except in the test of the 

 Blanchard boiler, by students Henderson, Hewitt, Poinier, and Post, 

 of the Stevens Institute of Technology, who, under the instructions 

 of the Chairman of the Committee, kept the log with commendable 

 exactness, and rendered very valuable assistance. 



The coal used during the whole series of trials was from the Buck 

 Mountain Coal Company, Philadelphia, Nathan Hilles, President 

 It was found to be of excellent quality, and the results of the test are, 

 therefore, the more valuable as a standard representing the efficiency 

 of good apparatus with good fuel. The analysis of this coal, as 

 determined by Professor Walter E. Johnson, is given as follows : 



Water. 0.390 



Gaseous matter, including some agate, volatile at bright red 



heat .• 5.515 



Carbon 91.016 



Earthy matter and oxyd 3 . 079 



100.000 



It would-be interesting to learn the constituents of the " gaseous 

 matter given at 5.15 per centum, but this the Committee were unable 

 to ascertain. If there were, however, any combustible gases, it is 

 exceedingly unlikely that they existed in sufficient amount to appre- 

 ciably raise the evaporative:efficiency of the coal, as the steam genera- 

 ting powers of the anthracites seem to be precisely proportional to 

 the amounts of carbon they respectively contain. This fact was well 

 proven by Professor Johnson, in the course of his very extended and 

 valuable researches upon the constitution and value of American 

 c'oals. (See Report on American Coals, p. 5S6.) The total heating 

 value of this coal, therefore, provided all waste could be prevented, is 

 readily calculated, and would be 13,197.32, " British thermal units ;" 

 i. e., one pound of this coal, burned without waste, should be capable 

 of raising the temperature of 13,197.32 pounds of water one degree 

 Fahrenheit. This would be equivalent to evaporating 13.65 pounds 



