AMERICAN INSTITUTE. 511 



Mr. McCarthy gave a description of an engine working with superheated 

 steam, which he had seen in England several years since. The steam waa 

 superheated in a chamber distinct from the boiler, and was worked cutting- 

 off at l-62nd of the stroke, giving very great economy of fuel, and con- 

 siderable mechanical effect. 



Professor Hedrick stated, that the effect of superheating steam was 

 precisely similar to that of heating air ; that gases, and all vapors, follow 

 the same general law, of increasing a definite fraction of its volume for 

 every degree of heat added ; and, that Prof. Pierce had determined, by 

 calculation and experiment, that the same amount of heat which would 

 raise water sufficient to form a cubic foot of steam at 212*^, would give 6 

 cubic feet of volume increment to any volume of air, large or small, to 

 which it may be applied. He himself had determined it to be 4 -{- a small 

 decimal, not 6 cubic feet, but even this would develope immense power. 



Mr. Seeley. — One cubic inch of water will form one cubic foot of steam 

 at 210*^. Now, a gas expands by heat one 500th of its volume for each 

 degree ; therefore, if you heat a quantity of gas from zero to 500'^, you 

 double its volume. But water at 212*^ boils, and you put lOOO'' more heat 

 into it, and only convert it into steam of atmospheric pressure ; yet that 

 much heat communicated to a gas would treble its volume. 



Mr. Grarvey said that method of calculating was not correct, for it 

 ignored the increase upon the increment ; in fact the compound interest. 



Mr. Fisher read a paper descriptive of the structure of the " Prosser 

 boiler," for generating steam. He considered it defective, and not able 

 to give the economy of fuel, which it is reasonable to expect from a well 

 constructed boiler. 



Prof. Reuben said that the mechanical effects of heat, as produced in 

 steam or air engines, are due to the difference of temperature between the 

 steam or air entering the cylinder, and that leaving it ; and in the best 

 Cornish engines that is only l-14th of the heat which the fuel can produce. 



Mr. Larned regretted that the most of the matter brought forward was 

 not of a definite and accurate kind. He hoped to come to the club to get 

 information ; but, with the exception of the remarks of one or two, the 

 information given was too loose and indefinite. Allusion had been made 

 to the Prosser boiler, and as he was the owner of the patent, he could give 

 his experience of it, which was ample. In using it he had tried it in every 

 form, and some defects, which were found at first, were readily obviated, 

 and now he found it a thorough, good and reliable boiler. 



Major Serrell made some remarks upon the relative economy of high 

 and low pressure engines, as used respectively in locomotives and on steam- 

 ers, and decided that the railroad locomotive gave a much greater amount 

 of force for the same consumption of fuel. 



Mr. Dibbin joined issue with Major Serrell, on the quantities of fuel 

 burned, and the distances run by the steamers instanced, and agreed to 

 ascertain the most reliable data for next evenino;. 



The Association adjourned to Wednesday. 



