174 Report of the Select Committee 
see, which eause explosions or breakings, and which could not bé 
calculated upon. 
Is there any thing which prevents the engineer from fastening 
down or over-weighting the valves of a common condensing en- 
gine ?—It would he folly for him to do so. 
Is there any thing which prevents him ?—Certainly not. 
Supposing the valves tc be so fastened down, doés not the 
engine immediately become unsafe ? —Yes, certainly it must; but 
it would be folly to fasten it down, because, if the engineer be at 
all acquainted with his business, he must know, that if the steam 
be raised beyond five or six pounds per inch in a condensing 
engine, the power of the engine will not thereby be at all in- 
ereased; the condensing property of the engine does not consist 
in a higher pressure of steam. 
What is your opinion as to the comparative safety of cast and 
wrought metal used in boilers ?—I consider that wrought iron is 
extremely safe, compared to cast iron. 
Then at all events, it is your opinion, that in steam-boats 
boilers of wrought metal should be used in preference to cast ? 
—No doubt about it. 
Do you think there is any material difference between the use 
of copper and wrought iron ?—No, excepting in the greater des 
gree of corrosion to y which iron is liable. 
Are you aware of there being any considerable difference in 
the consumption of coals, necessary to produce any given power 
in condensing and high pressure engines ?—I consider that the 
one will work with as little coal as the other; in all high pres- 
sure engines and condensing engines I have heard of, I find little 
or no difference, and those who have them tell me they burn as 
much coal in the high pressure engine as in the low pressure en= 
ie I have understcod that Woolf’s engine does save coal. 
Do you know that to be the fact >—I do not, because J never 
attended any experiments ; but I have heard “i from so many 
people that I cannot but believe the fact is, they save coal. 
If a high pressure steam-engine had a wrought-metal boiler; 
either of iron or copper, constructed by a competent engineer, 
with safety-valves in proper order, and a mercurial gauge, should 
you then think yourself in any danger in a steam-boat propelled 
by such an engine ?—Certainly not, if a competent person had 
the superintendence of it. 
Mr. AtuxanvderR GaLtoway’s Evidence. 
What is your profession and plice of abode ?—I am a me- 
chanist and engineer, residing in Holborn. 
Do you know any thing of that paper [showing @ paper to the 
witness] 2—I have seen it. 
Do 
