088 Transactions of the American Institute. 



how force is modified by velocity, which constitutes so powerful an 

 element of the momentum. The regularly increasing pressure of 

 steam, is a gradually augmenting strain upon the boiler, in which the 

 momentum is deficient in velocity ; and the natural effect would seem 

 to be, to rend or split, and not to burst up the boiler, much less to tear 

 it in fragments, throwing it, as in many instances, hundreds of feet 

 from its place, and scattering ruin in every direction. The telegraph 

 to the press of Philadelphia has just communicated that, on the morning 

 of the 7th of August, at St. Louis, the boiler of the Union Steam 

 Flouring Mills, of Yager & Company, exploded, instantly killing 

 John Scott, engineer, and James P. Jones, fireman, and that the 

 entire. eastern side of the building was blown out, and fragments of 

 the boiler were thrown to the distance of half a mile. The idea that 

 the water in the boiler, at the moment the case gives way, is converted 

 by a sudden flush into steam, and thereby produces the explosion, we 

 are able to show cannot be true. It is in every respect improbable ; 

 it is, indeed, equivalent to the supposition that the water of the boiler 

 explodes, which is absurd. We will produce an instance of a disastrous 

 explosion when there was no water at all in the boiler. 



It must be understood that we do not deny that boilers have been 

 bursted, that is, rent and split open, by steam. We very well know 

 that this has often happened, and that it is inevitable when the press- 

 ure acquires a force beyond the strength of the boiler. Our notion is 

 this, that in many explosions of steam boilers the facts are such as 

 can only be accounted- for by the application of a sudden, prodigious 

 and explosive force, different from the graduated increasing strain of 

 the pressure of steam. We shall take for illustration an instance of 

 the explosion which occurred at the cotton mills on Duke street, 

 Lancaster, Pa., in the summer of 1867. It was on the 13th of July ; 

 the weather was clear, a dry mist only prevailing in the early morning. 

 It took place five minutes before six o'clock, at which hour the mill 

 was to have t been started. The mill and all the machinery were new ; 

 the engine and boilers, of which there were two, situated side by side, 

 were of the most approved construction. The engine-house was of 

 brick, one story high, built against the eastern end of the mill, the 

 wall of which, eighteen inches thick, formed one of its sides ; the 

 other walls of the engine-house were thirteen inches thick. The 

 boilers were sixteen feet long and fifty inches in diameter, each hav- 

 ing twenty-two flues. There was a sufficiency of water in them, it 

 being four inches above the lowest gauge, and the pressure of the 

 steam was eighty-five pounds to the square inch, which was within 



