G38 Transactions of the American Institute. 



it would be necessary to break all these tubes at the same instant that 

 the shell gave way ; but these tubes did not break at all. The stays 

 were drawn out, although they had strength enough to support two 

 or three times the pressure upon the head ; and, besides these tubes, 

 there was the strength of the shell itself. 



I have no doubt whate ver that the rupture of the boiler was caused 

 by the contraction of the bottom of this shell, while these lower flues 

 were expanded, causing a transverse rupture first, which caused the 

 hissing sound heard by the fireman immediately before the accident ; 

 the bottom of the shell was opened at one end of the longitudinal 

 rupture, and' the sheet carried edgewise so as to tear it from one line 

 of seams to the next ; then the pressure of the steam threw open 

 these sheets, thus loosened and separated, and threw the two ends of 

 the boiler to the places where they were found. I shall endeavor, on 

 another evening, to demonstrate the correctness of this conclusion. 



The President — That there is no weight in the argument that the 

 pressure in the boiler is increased vastly by the decomposition of the 

 steam, may be seen from the fact that when decomposed two volumes 

 of steam become two volumes of hydrogen and one of oxygen gas ; 

 so that it will only occupy, at the most, one-half more space. 



Dr. Van der Weyde — I do not think that meets the theory, which 

 is that an explosive mixture is formed. That is fallacious, however, 

 for it is well proved that steam, in contact with red hot iron, can only 

 be decomposed by its oxygen uniting with the iron, leaving the 

 hydrogen alone, which is not explosive. 



The President — And if the iron takes up the oxygen, the hydrogen 

 will occupy only the same space previously occupied by the steam. 



Dr. Van der Weyde expressed the opinion that the over-pressure 

 of the steam, the boiler being unprovided with stays along the central 

 portion, caused it to burst ; and stated that the pressure on each head, 

 the boiler being ten feet in diameter, was more than a quarter of a 

 million pounds. The true remedy is to make smaller boilers. Trav- 

 eling on the Ohio last summer, and finding his room over the boiler, 

 he went to see what the pressure was, and found it 140 pounds; but 

 even that was safer than a pressure of twenty-seven pounds on the 

 Westfield boiler, because instead of one large boiler they had several 

 small ones. If the diameter of the boiler is two feet instead of ten 

 feet, the pressure upon the head is only one twenty-fifth ; and one 

 twenty-fifth of 1G0 pounds is much less than twenty-seven pounds. 



At the suggestion of Prof. Phin, the discussion upon the subject 

 ^vas deferred until Mr. Wiard should have explained his own theory. 



