2 
‘on Steam-Boats. 179 
Have you given any attention to the construction of engines 
for steam-boats ?—I never have; I have made steam-engines, 
but not for steam -boats. 
The object of this Committee being to inquire into the con- 
struction of engines for steam-boats for the safety of passengers, 
have you any thing to communicate to the Committee on that 
subject ?—I have only to observe, that I make them in cast iron, 
and I have proved them by an hydraulic press made for the pur- 
pose, and have gone as high as 250 pounds to an inch, and that 
I considered enough ; nothing happened; and I mean the next 
time to try what they will bear, and I have no doubt they will 
bear from 700 to 1000 pounds to.an inch, for I believe they can 
be made now stronger than wrought-iron boilers ; wrought-iron 
boilers being riveted together, cannot be so strong as those east 
in a solid mass. 
May not there be some imperfection in cast iron, which may 
not be discoverable without an accident happening ?—It is 
scarcely possible, if it undergoes the trial I speak of by pressure 
before it is put to work. 
May not that trial to which it may be exposed, though no ac- 
cident happens immediately from the trial, be injurious to the 
boiler itself?—If it is made so as to be strong enough to stand 
the pressure of 500 pounds upon the inch when it only wants 
fifty, I suppose that proves it to be quite out of danger. 
Are you aware that there is a difference between trial made by 
water-pressure at a certain temperature, and the exposure of 
cast iron to the action of fire repeatedly, by which the metal 
is heated to a very high degree, and consequently expanded and 
then cooled again down to a temperature very far indeed below 
that which it was before exposed to?—I have seen the effect of 
that; a boiler I have made has been composed of three tubes, 
one a large one and two smaller ones below; those lower tubes 
which are exposed most to the fire have cracked generally by 
cooling after the engine has done working; I have known that 
in three or four instances; perhaps, in an hour after the engine 
has done working, the tubes below have cracked and the other 
not. ) 
Are you not aware that the tubes which were so cracked by 
the application of fire, might have stood the water-pressure of 
which you before spoke, to almost any conceivable amount ?— 
Yes, I suppose they would. 
~ In case of explosion,—which would produce the greatest mis- 
chief, that of a cast or of a wrought-iron boiler ?—I suppose the 
greatest danger would be in the wrought-iron boiler. : 
For what reason ?—Because the cast iron uniformly cracks at 
the bottom underneath the large part of the boiler; the pk 
M 2. tubes. 
