2 On the means of safety in Steam Boats. 



"In all cases where fatal accidents have occurred, the explosion 

 appears to have been due to other causes than the mere expansive 

 force of the steam that would be formed when the boiler is in proper 

 order and supplied with water. 



" If we suppose that the supply of water is impeded or checked 

 altogether, the level of that in the boiler must descend, and parts ex- 

 posed to the action of the fire may become dry ; such parts may then 

 become heated far beyond the temperature of the water beneath. 



" If by any cause the water from beneath is brought into contact 

 with the vapor and heated surface of the boiler, it will be instantly 

 converted into steam of great expansive force, and in quantities for 

 which the usual safety valves are not sufficient to provide an escape ; 

 an explosion must therefore ensue. — p. 96. 



" The water may be brought into contact with these heated parts 

 of the boiler, or with the hot vapor, by the very means that would, in 

 other cases, be applied to diminish the danger. Thus, if the safety 

 valves should be opened, the water which was before boiling quietly, 

 will suddenly rise into violent ebullition ; or if the feeding apparatus 

 begin again to act, the level of the water will be raised. In both 

 cases, a contact will take place Vv^ith the red hot surfaces, and with 

 the intensely heated steam. This is in truth, almost the sole cause 

 of the explosions of boilers, whether of low or high pressure." — p. 97. 



" Boilers, when the fire is made within, or when the return flues pass 

 through them, are obviously far more subject to accidents arising from 

 this cause, than those heated from without. Lovv^ pressure engines 

 are as liable to them as high, and it is confidently believed, that very 

 many explosions are to be attributed to this cause against which the 

 usual safety apparatus furnishes no protection." — p. 98. 



This conclusive explanation appears to be sustained by the exper- 

 iments of Prof. Johnson of the Franklin Institute, given in your last 

 number, on the rapid production of steam by the immersion of red 

 hot iron , and the rate of production might be estimated on the prin- 

 ciple of latent caloric, according to Dr. Black, transferred from the 

 mass of sensible beat. 



As the readiest description of my expedient or means of alarm or 

 notice to he given hy the subsiding water itself, I annex the specifica- 

 tion of the invention — intending to claim a patent for it at maturity. 

 It is well known that a privilege of this kind is not often a remunera- 

 tion for the time bestowed on the subject of it. Yet the usefulness 



