62 Report of the Select Committee 
.Be'so good as to state which, and why?—I conceive there is 
no danger whatever in the use of high pressure steam-engines ; ; 
and for this reason, that in general, for an engine that is in- 
tended to be worked with high steam, the materials are made 
stronger in proportion than the materials used for steam of low 
pressure. 
What are the precautions which you think it necessary to take, 
in order to render a high steam-engine perfectly safe from acci- 
dent >—The materials should be made strong enough, and there 
isno difficulty in doing that; and there is a good deal depend- 
ing on the construction of the safety-valve, which should be so 
constructed as to go quite easy and without any possibility of 
sticking. 
Do you not think it of importance, if not necessary, that a 
boiler should have two safety-valves ?—Certainly; and every high 
pressure steam-engine that I attend to has two safety- valves. 
Do not you confine one of those from the engine-man ?—Not 
in any instance. 
Should you or not think it necessary, on board a boat for pas- 
sengers worked by a steam-engine, that there should be an ad- 
ditional safety-valve to the boilers which the engine-man could 
not come at to prevent its operation ?—That would certainly be 
very desirable, and I should think necessary. 
Have you any choice, in peint of safety only, between a boiler 
constructed of cast iron or of wrought iron?—Were J to have a 
boiler where I wished to have.the greatest strength, I would cer- 
tainly have it made of cast iron; I have not one doubt that a 
cast-iron boiler can be made much stronger than it is possible 
to make a wrought iron one; in fact, the explosions that we 
have had in.Cornwall have all been in wrought-iron boilers, but 
}-never had one in cast-iron boilers,. nor have we had an acci- 
dent from high pressure steam ; ail the accidents have been from 
Jow pressure steam in Cornwall. 
Ta what do you attribute that?—I attribute that to the 
boilers not having their proportionate strength to the weight 
they ought to bear, that the high pressure steam-engines have. 
Of what nature are those failures which usually happen in the 
«wrought iron boilers ?—The one which I witnessed the explosion 
of, thnieww off the man-hole door. 
Do you mean that the bolts by which the man-hole door was 
secured, gave way?—Yes. 
~ Are:there not man-holes to cast-iron boilers >—There are, 
Then might not the best constructed and the strongest cast- 
‘jron boilers have been equally liable to the accident you. have 
been: mentioning, from the. mere failure of the bolts, -by which 
the man-hole door was secured ?-- Certainly not, and for this 
reason, 
