Polytechnic Association. 705 



the explosive energy is but the explosive force suddenly and indefi- 

 nitely increased, striking every part at the same instant with a resist- 

 less expulsive power. The effect would necessarily be to overthrow 

 all surrounding objects in opposite directions; and as the only point 

 in which theue could be sufficient strength to react against so mighty 

 a force was the foundation, the reaction from thence naturally lifted 

 the boiler from its position. In being thus lifted with the northern 

 end probably first raised, the explosive force striking it at the instant, 

 discharged it with the prodigious power that was sufficient to hurl it 

 TOO feet, while the other end was sundered and driven in the opposite 

 direction. All the debris of this destructive explosion exhibited, by 

 the position of the fragments, the fullest evidence that the force had 

 acted as we have indicated — forcing all things apart, just as an explo- 

 sive power would naturally do. 



We believe, then, as the facts are all reconcilable with the theory of 

 an explosive force ; as such force could only result from some collec- 

 tion or accumulation of gases in the boiler : as the water, by its 

 decomposition, afforded an abundant source for the supply of explo- 

 sive gases ; as water is decomposed by currents of electricity passing 

 through it ; as immense quantities of electricity are generated in the 

 production of steam ; as no object can contain more than a certain 

 quantity of electricity, and when a surcharge takes place an electric 

 spark inevitably ensues, carrying off the surplus ; as this electric 

 spark fires and explodes the oxygen and hydrogen gases when it 

 touches them, we believe that it was the explosion of those gases, 

 accumulated in this boiler on the morning of July 13, 1867, fired by 

 an electric spark, which caused that disaster ; and further, we believe 

 that all the most violent explosions of steam boilers which have 

 occurred were owing to a similar cause. 



If this be true, the most important inquiry remains : Is there no 

 remedy, and what are the means of prevention ? We think there is 

 a remedy, and that it consists in very simple and direct means of pre- 

 vention. Care and skill in the engineer are, of course, indispensable 

 qualifications. The safety valve should never be neglected ; but 

 especially should there be an arrangement of metallic conductors, 

 with points fixed within the boiler in close proximity to the upper 

 surface and passing through the case of the boiler, be connected with 

 some conducting material communicating with' water or the earth, in 

 order to lead the electricity off from the interior of the boiler, and 

 thereby prevent an accumulation and discharge. By such means an 

 [Inst.] 45 



