726 Transactions of the American Institute. 



highest point of its heating surface, can be exploded with such com- 

 plete destruction as to reduce it into mere debris, and hurl the frag- 

 ments in all directions with a force that no ordinary construction of 

 building or vessel could withstand. 



2d. That the pressure required for so devastating an explosion is 

 the very moderate one of fifty-three and one-half pounds per square 

 inch. 



3d. That with only a wood fire, generating a far less quantity of 

 heat in equal time than a coal fire, there were required only thirteen 

 minutes to raise the pressure from the inspector's working allowance 

 of thirty pounds per square inch, to the exploding pressure of fifty- 

 three and one-half pounds per square inch, showing that a few min- 

 utes' absence or neglect of the engineer, coupled with an overloaded 

 or inoperative safety-valve, are all that are needed to produce the 

 most destructive steam boiler explosion, even with an old and 

 unequally braced boiler, in which it might be supposed a rupture of 

 the weakest part would precede other fracture, and allow the escape 

 of the pressure without doing further injury. 



4th. That in accounting for either fact of an explosion, or for its 

 destructive effects, there is no necessity for hypothesis of low water, 

 enormous pressures, instantaneous generation of immense quantities 

 of steam, superheated steam, the formation of hypothetical gases, 

 development of electricity, etc., etc. . The most frightful catastrophe 

 can be produced by simply gradually accumulating the pressure of 

 saturated steam to a strain at which the strength of the boiler yields, 

 nor need that pressure be much above what is ordinarily employed 

 with boilers of this type. 



5th. That there is no flashing of the boiler water into steam at the 

 moment of an explosion. On the contrary, with the exception of the 

 small portion of this water vaporized (after the reduction of the press- 

 ure owing to the rupture of the boiler) by the contained heat in it 

 between that due to the temperature of the steams of the exploding 

 pressure and of the atmospheric pressure, it remains unchanged, and 

 is thrown around, drenching the objects near it, and scalding whom- 

 ever it falls upon. 



6th. The weakest portion of the boiler braces was in their welds. 



7th. The equal stretching in all directions of the boiler-plates 

 between the screw-bolts, due to their bulging under the pressure, was 

 sufficient to permit the slipping out of the bolts without injury to 

 the screw-threads either upon them or in the plates. 



8th. That this experiment has conclusively disposed of several 



