on Sieam- Boats. 95 
wall. It states the consumption of coal, and the work done by 
every engine therein named, from which it appears that the 
average work of engines now in the county of Cornwall, is to 
Taise about twenty million pounds of water one foot high, by the 
consumption of one bushel of coals; that by the introduction 
of high pressure steam under the best mode of management, am 
effect equal to from forty-three to forty-five million pounds of 
water is raised the same height by the same quantity of coal, 
thereby producing above double the effect. , 
Do you apprehend that condensing or low pressure engines 
are liable to be blown up by the carelessness and inattention of 
the engineer conducting them?—lI apprehend equally so with 
high pressure engines; and I am of that opinion from facts which 
have reached me. InFrance, at Crusog, some very good engines 
were erected by Mr. Wilkinson, at a very large work, They, 
were on Bolton and Watt’s principle; one of them blew up and 
killed several people. I have heard of other instances, but they 
are not within my own knowledge. 
Do you conceive that the mercurial gauge may be applied with: 
ease to the high pressure boilers, so as to produce safety, as cer- 
tainly as the column of water, which is in fact a water-gauge, 
which is usually applied to the low pressure?—I] do most un- 
doubtedly think that, provided the mercurial gauge be of a 
sufficient bore; and I think, in some respects, it would have the 
advantage of the water-gauge, as being less liable to accidental 
obstruction. 
Do you conceive that there is any difficulty whatever in con- 
structing a safety-valve, so as to operate with certainty, and to 
be safe from any impediment which the engineer might inten- 
tionally place in the way of its operation ?—I do think such a, 
safety-valve can be constructed. 
Do you apprehend any additional considerable expense would 
be thereby incurred ?—Not any considerable expense; we have 
done it to all the boilers we have lately superintended the erec- 
tion of, putting them under lock. 
Mr. Joun Cortince’s Evidence. 
What profession are you of ?—An engineer and iron-founder. 
In the course of your profession, are you conversant with the 
nature of steam-engines ?—I have made several. 
Where do you live ?—In Bridge Road, Lambeth. 
I believe you are the patentee of the patent axle-tree ?—I am. 
Did you go to Norwich in consequence of the accident that 
happened to the steam-boat there ?—I did, in company with 
Mr. Donkin and Mr. Brown. 
Did you go at the request of any person ?—No, it was volun- 
tary, 
