ae 
ee, =. 
2 On the means of safety in Steam Boats. 
“Ty 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, t the level of that in the boiler must descend, and parts ex- 
posed to the acti@p 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 5 
an explosion must therefore ensue.—p. 96. 
The water may be brought into contact with these eee parts 
of the boiler, or with the hot vapor, by the very means that would, in 
other Caste. be applied to diminish the danger. Thus, if the safety 
valves 
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 with 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. Low 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 heat. 
As the readiest description of my expedient or means of alarm or 
notice to be given by the subsiding water itself, 1 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 
Se ae tee eee eee Ne ee ROR EEE eae ee see ee eee 
