on Sieam-Boats. ah} 
Was the explosion of that boiler owing to the weakness of the 
metal, or improper construction ?—It was, perhaps, from the 
weakness of the metal; I cannot answer that question exactly. 
It was a cast-iron top; it was the upper part of the wrought 
iron, joining to the cast iron, that gave way. Another instance 
was at Shersiff-hill colliery, where the boiler was projected over 
the engine-house ; there was no other damage done, excepting 
breaking a capstan. 
What sort of boiler was that ?—It was a round wrought-iron 
boiler. Another instance was at the foundry near Stourbridge, 
where the boiler bursted, and one man was killed. 
In all the accidents you know of, did they arise from the im- 
proper construction of the boiler, or from the ignorance or mis- 
management of the engine-man ?—J have no doubt that either 
the one or the other caused all the accidents that ever hap- 
pened. 
Are not common or low pressure engines often used at a 
higher degree of pressure than was desi igned by the person who 
constructed the boiler ?—Yes, and particularly in steam-beats. 
I have had more than once occasion to correct that, or to re 
monstrate with the engine-man.. I should say, that this danger 
is considerably increased, from a number of the boilers on board 
the steam packets having large flat sides. 
Do not the engine-men, in many cases, increase the pressure 
of the steam in the boiler, although it be of no additional ad- 
vantage whatever in increasing the power of the engine >—Yes, 
I think I may say so, if applied to the low pressure engine or 
condensing engine. The additional force of the steam subjects 
the engine to a number of inconveniences. 
Have you been concerned in making boilers for high pressure 
engines ?>—Yes. 
Do you think that boilers for high presqine engines can be so 
constructed as to become useless betore't they are dang rerous?— Yes, 
Upon what principle ?— Upon the principle of having the 
exterior part of the boiler independent of the flue, so much so, 
that while the flue is injured by the current action of the fire, 
the exterior part of the boiler remains, as to strength, unimpaired ; 
and I conceive that a boiler thus formed, when the flue has been 
worn very thin, and then exposed to a greater pressure than it 
could sustain, the thin parts of the flue would act as so many 
safety-valves. From my experience in regard to these boilers, I 
know that when they have been worn for some time, you cannot’ 
have them tight. 
You are speaking here of boilers constructed of wrought iron? 
—Yes; I speak of them because I have so constructed them’; 
but I have uo doubt that cast-iron boilers, if constructed upon 
the 
