96 Report of the Select Committee 
tary, from an impression the public mind would be alarmed, and. 
wish to know the cause of the accident. 
Did you see the boiler, or any of the remaining part of that 
éngine >—I did. 
Do you atttibute the eatise of that explosion to the construc- 
tion of the boiler >—I do. 
Be so good as to state what it was?—The boiler was com- 
posed entirely of wrouglit iron, except one end, and that was 
eapped with cast-iron. 
The cylindrical part was made of wrought iron ?}—Yes. 
Tt was a high presstire boiler ?—It wags. sehen 
Originally it had all been wrought iron ?—It had, T believe. 
But upon an alteration they put one end of cast iron?—Yes. 
Was not such a conjunction of ‘metals in such a place very 
dangerous ?}—Certainly. 
Principally because the expansion of the metal is totally dif 
ferent in one and the other ?—Yes. 
What is your opinion, as an engineer, in respect to the ma~ 
terial of which boilers in gener al should he made ?—Any material 
under very severe pressure is liable to fail, and cast iron for this 
reason, because in all large bodies we find that the air cannot 
wholly escape im the act of fusion, I have occasionally had 
large masses of cylinders and pans to break up, and we find fre- 
quently cells where the air could not escape, so that we are never 
certain as to the solidity of cast iron there is’ certainly a much 
greater dependence upon wrought iron or upon wrought metal 
perhaps it would be better to gnclude copper. 
In wrought iron there is danger from cold shut ?—Yes. 
Supposing an accident should happen to any boiler, which 
would be most likely to be attended with the greatest mischief; 
a cast-iron or a wrought-iren boiler ?—Cast iron, because cast 
iron flies off in fragments, and wrought, from tenacity, only 
rends. : 
Did you ever hear of an accident in a wrought-iron boilér 
when it has exploded, that has done any considerable mischief ? 
—I was almost upon the point of believing, that wrought-iron 
boilers would have resisted a degree of pressure, 1f properly made, 
beyond what I find they will do; because an accident has oc- 
eurred at Malden, where a boiler, nineteen feet long, was blown 
off from the seat of its connexion with the base. I have found, 
in making wrought-iron boilers myself, that if I make them of 
metal of a considerable substance, that they cannot be so well 
united to make them steam tight; it 1s a very difficult thing to, 
do; how far that is the case with copper, I have no acquaintance, 
but perhaps it would not be precisely the case with copper; the 
rivets that are applied to wrought-iron boilers are put in hot, 
and 
