68 Hazard on the Explosion of Steam Boilers. 



the tube became red hot ; no steam or water escaped from 

 it, notwithstanding the steam guage indicated a very high 

 pressure ; a wire was introduced into the hole to ascertain 

 that it was free. The generator was then suffered to cool 

 to a black heat, when the steam commenced issuing from 

 the hole with great violence. Another experiment was to 

 heat two cast iron bowls of equal dimensions, the one black, 

 the other red hot, and then pour equal quantities of water 

 into both : the cooler bowl uniformly evaporated the water 

 first. I have frequently noticed very hot pieces of iron, 

 when thrown into a blacksmith's slack trough, lie red hot 

 for some time under the water, apparently surrounded by an 

 atmosphere of heat, without throwing any steam to the sur- 

 face. This will never be the case if the tongs be plunged 

 into the water with the hot iron ; as their heat, in some part, 

 is only sufficient to raise steam, and not sufficient to prevent 

 the water from coming in contact with them, and through 

 them, with the whole mass successively. From the above 

 facts, Perkins 1 explanation of the bursting of boilers, will, I 

 think appear very plausible : it is this ; that the water is suf- 

 fered to get so low as to bring a portion of the boiler, not 

 covered with water, in contact with the fire ; this becomes 

 red hot, and imparts its heat to the steam ; the redness grad- 

 ually extends itself below the water, which is at length repel- 

 led from the boiler, and thrown up among the hot steam, 

 (like a pot suddenly boiling over,) which surcharged steam, 

 immediately imparting its excessive heat to the water, forms 

 steam of the greatest power and occasions the disastrous 

 explosions. 



In the late accident on board the Oliver Ellsworth, it 

 seems to be impracticable to ascertain what was the state of 

 the water in the boiler ; but supposing it to have been at the 

 proper height, may not the motion of the vessel, from a 

 head sea, have left portions of the boiler exposed to the fire, 

 for a length of time sufficient to make them red hot, and the 

 above theory be thus rendered perfectly applicable ? Should 

 this be the fact, it appears to me an additional security 

 would be obtained, by having the boiler divided by parti- 

 tions, which though not tight enough to prevent a regular 

 communication from the supply pump, and steam pipe, to 

 every part of the boiler, would still be sufficiently so to prevent 

 the water from rushing, in a body, from one extremity to the 

 other, thus leaving portions of the boiler unprotected from 



