Polytechnic Association. 7(37 



the whole boiler through a space of 78.74 feet ; and, water included, 

 44.99 feet. Owing to the greater inertia of the lower part of the 

 boiler, and particularly of its inelastic burden of water, the principal 

 part of this work was undoubtedly performed upon the upper portion 

 and steam chimney of the boiler, weighing probably 6,000 pounds ; 

 and, if entirely expended in this direction, the work thus done was 

 equivalent to raising this 6,000 pounds to a lieight of 525 feet. 



This latter case is capable of treatment in quite a different way from 

 the above. As the boiler was completely torn in pieces, the steam 

 must have expanded pretty equally in all directions, except where 

 checked in its downward movement, and may probably be treated as 

 if forming a rapidly expanding hemisphere of vapor, its center being 

 in the steam space of the boiler. 



The expansion of this hemisphere would have continued until the 

 tension of the steam was reduced to that of the surrounding atmos- 

 phere, and would have continued through a mean distance, as given 

 by an approximate estimate, of 4.5 feet. The mean pressure would 

 be twenty-five pounds above the atmosphere nearly. 



The area of cross-section of the steam drum was 4,071 square inches, 

 and 4,071 x 25 x 4.5=457,987.5 foot-pounds, the amount of work done 

 in its projection. 



The weight of the steam drum, which was one-quarter of an inch 

 thick, six feet diameter, and eight feet and eight inches high, was, 

 with its braces, 2,500 pounds, and 457,987.5^2,500=183.2, the height, 

 in feet, to which the drum might have been thrown by the simple 

 expansion of the confined steam. In fact, the steam drum had 

 attached to it, when found after the explosion, a considerable part of 

 the boiler top, which, being comparatively light, and being acted upon 

 by similar pressures, must have considerably accelerated, rather than 

 retarded, its ascent. 



Still another calculation may be based upon the observed effects of 

 this explosion. The steam drum was observed to rise at a high 

 " angle of elevation," and fell at a distance of 450 feet from the start- 

 ing point. 



If this angle of elevation was sixty degrees — and the general 

 impression was that it was not less — the height due to the range, 

 450 feet, neglecting the resistance of the air, would have been 

 E 450 



h = = = 260 feet. 



2 sin 2 a 2 X .866 



The retarding effect of the atmosphere causes our figure to be some- 



