566 TRANSACTIONS OF THE 



Steam or hot air being exhausted into a surface condenser, may 

 bs made to yield the heat which vitalized them, to the feed water 

 or air. But the condensation is so slow, that the saved heat does 

 not compensate for the lost time. Again, hot air or steam may 

 be exhausted into the external air, through the feed water, thus 

 saving a fraction of their heat. Yet this operation does not re- 

 move the grand objection — comparative bulk. Again, steam, 

 unlike air, may be instantaneously reduced in volume, 1,700 

 times, by the withdrawal of the heat which originally expanded 

 it. Practically, an approximately vacuum may thus be formed, 

 and a portion of the escape heat may also be returned to the 

 boiler, an invaluable result in marine locomotion. 



But again, it is proposed to obviate the destruction of the 

 heater, by bringing the feed air into direct contact with fire, thus 

 allowing the gaseous products of combustion to expand with the 

 air, and thereby applying to some good purpose, whatever is sup- 

 plied to the heater. 



The radical difficulty is now, not only more moved, but it is 

 increased; lor combustion under the maximum pressure must be 

 supported by an additional supply of air; but it is proposed to 

 generate steam, by the injection of water into the same heater, 

 and to work the die, the gases, and the vapor in the same cylin- 

 der. Now if such a locomotive proves successful, inasmuch as 

 the superiority of the steam dementis mathematically and prac- 

 tically certain in other cases, why should that success be attribu- 

 ted to the source which is in all cases known to be inferior 1 



The application of steam to the cylinders prevents in propor- 

 tion to its quantity, that serious drawback, oxidation, and im- 

 msnssly increased friction; or does it remove any radical and 

 primary objection, or does it impart any efficacy to the air ? Sepa- 

 rate estimates of the dynamical effects of these agents, can alone 

 lead to a correct knowledge of their relative or combined value. 



But again, it is proposed to obtain power by the repeated re- 

 generation of the same fixed quantity of air, under high artifi- 

 cial pressure. Assume that one ounce of coal will double the 

 volume of one cubic foot of air by raising its temperature 500 

 degrees. Take 100 cubic feet at the atmospheric pressure : 



1st. One hundred ounces will double them, giving an effective 

 pressure of 1,500 lbs. upon a piston. 



2d. If they are first compressed artificially into one foot of 

 space, thus exerting a pressure of 1,500 lbs., one ounce will 

 double their volume, giving as before, an effective pressure of 



