186 [Assembly 



with incandescent metal, and heated from 1600° to 2000° above 

 its normal temperature. 



The low capacity for heat which has been found by Mr. Frost 

 in dry steam, accounts for the fact that explosions arising from 

 the cause we have referred to, are often preceded by a diminu- 

 tion in the force with which the engine works. It also enables 

 us to explain how it happened that although the very action pro- 

 posed by Mr. Frost, namely, the heating of dry steam, has been 

 employed for many years in the " Steam Chimneys" so familiarly 

 known, no very important advantages have been gained by their 

 use. In this case the steam has parted with its temperature to 

 the cylinder and steam passages just as rapidly as it has acquir- 

 ed it. 



In this cause also we are to find the reason of the difl&culties 

 which Mr. Frost has experienced in applying the principles de- 

 duced by his experiments to the actual working of an engine. 

 These difdculties he has overcome in an engine of small size, by 

 methods extremely ingenious and suflSciently simple. 



It should be considered that we know that incandescent me- 

 tal may drive off water in globules, and that this incandescence 

 is often produced in particular spots of the boiler, by means of an 

 accidental high heat produced by peculiar arrangements of fuel 

 and draught of air, and particularly where there is not enough of 

 water in the boiler. In such cases an explosion may be the con- 

 sequence. 



It should also be considered that more of the metals than is 

 usually admitted are capable of decomposing steam when intense- 

 ly heated, and are thus oxidated. These considerations show 

 that there must be difiiculties or even dangers in the use of dry 

 steam, and ought to be taken into account- in any attempt to re- 

 duce Mr. Frost's principles to practical application. 



JAMES RENWICK, 



H. MEIGS, 



HENRY R. DUNHAM, 



Committee. 



