Polytechnic Association. 689 



the allowed maximum. The engineer, a careful and experienced 

 hand, was engaged at the time, with his assistant, in oiling the engine. 

 The boiler next to the street exploded, completely demolishing the 

 engine-house. The larger portion, severed from the rest, was hurled 

 through the northern wall, and, with two rebounds from the earth, 

 landed at a distance of 700 feet against a tree, which probably saved 

 the house before which it stood. The engineer, the mill agent, and 

 two other persons were killed. The boiler weighed 6,300 pounds. 

 It was parted by the explosion, and the other end, with a small sec- 

 tion of the boiler-cased flues, was thrown south about forty feet. The 

 engine-house was roofed with tin, which was- torn to fragments and 

 scattered in various directions, as were other parts of the building. 

 The pulverized mortar appeared to have been plastered against the 

 wall of a dwelling house sixty feet south on the adjoining lot. The 

 other boiler was driven sideways through the eighteen inch wall of 

 the mill and lodged ten feet within, much bent out of shape and about 

 half of the flues broken. It was near this spot that the mill agent and 

 two other .persons were killed. Bricks were thrown to a great distance, 

 some through the windows of the house across the street, and a hole 

 was knocked in the wall of the house on the same side of the street, 

 south, forty feet above the ground. The prodigious force of the 

 explosion is shown by this detailed account. It is to be considered 

 that the same force, so far as it was caused by the pressure of steam, 

 was exerted in both boilers, for there is nothing to warrant the sup- 

 position that the pressure was not the same on each, or that one was 

 not as strong as the other. If the force was irresistible in one, as 

 shown by the event, why not in the other ? 



We do not think this cpaestion can be solved by the theory of the 

 steadily increasing pressure. The immense force of steam is observed 

 in all its regulated manifestations. The pressure it exerts is equal in 

 all directions. When a breach in a boiler, caused by excessive 

 pressure, occurs at one extremity, the issue of steam through the 

 breach diminishes the pressure upon the other extremity as on the 

 rest of the boiler, the pressure being an impelling force acting against 

 opposite points, in all parts of the boiler. All these points react by 

 resistance, and whatever diminishes the impelling force at any point 

 necessarily weakens it at every other ; and" the effect of the pressure 

 breaking through a boiler at one end could never be to drive the 

 other end in an opposite direction ; the tendency would be, by lessen- 

 ing the impelling force there, to give the reactionary or resisting 

 power a movement in the same direction with the steam, issuing 



[Inst.] 44 



