178 Report of the Select Commiitee 
The Committee being desired to report upore-the safety of 
steam-boats, and upon the safety only, they will be much obliged 
to you to communicate what you know upon the subject ?—Re- 
specting high pressure steam, which I shall confine myself to at 
this moment, I will engage to make a boiler, or direct one to be 
made, which I will defy any engineer or other person to blow up 
.or burst ; and I have lately erected five boilers; and I am ready 
to prove ‘to any gentleman, and even to any engineer, that they 
cannot destroy them. 
Upon what principle were those boilers constructed ?—Those 
boilers that I have fitted up, with the different apparatus for 
making them secure, were made of wrought iron; but I do not 
mean to say cast-iron boilers cannot be made secure. I recom- 
mended to Mr. Martineau, for whom I erected them, that as 
there had been an accident in his neighbourhood, he ought to 
have a boiler to bear three times the pressure he meant to put 
upon it; and if it did bear that pressure, and they applied two 
safety- -valves with a mercurial steam- -gauge, properly weighted 
and adjusted (one of those safety-valves should be at the will of 
the person about the boiler, and the other no man should be 
able to get at),it would be impossible to explode a boiler of that 
description. J saw the boiler after it was exploded at Wellclose- 
square, and alsa conversed with one of the men that was saved, 
who told me, that he had carried an additional weight to put on 
the safety-valve just before it exploded, that the mercurial gauge 
there was plugged up, so that it was useless; besides which, in- 
stead of the safety-valve being weighted equal to forty-five pounds, 
they added a double weight which increased it to ninety pounds 
weight upon an inch, and the boiler was very improperly made. 
I conceive that a steam-engine boiler, constructed as it ought to 
be constructed (I do not mean to say if you put a boiler into the 
hands of men not acquainted with it, without the proper safety- 
valves, there may not be danger)—but if properly constructed 
there is no danger. 
Would you not recommend on board steam-boats, wrought- 
metal boilers to be used in preference to cast ?>—Certainly; I 
have made some discoveries myself in the boilers I have put up, 
which makes them perfectly safe. 
Do you know any thing respecting the comparative comsump-. 
tion of coals in high and low pressure engines ?—Not from my 
own actual experience, only from what gentlemen have told me 
where I have done business. 
Mr. Joun Hatw’s Evidence. 
Where do you live ?—At Dartford. 
What are you by profession ?>—An engineer and millwright. 
Have 
