168 "  Repori of the Select Committee 
How many have you?—I think it is three; but I have only 
been in one of them. Si dle 
- Do you know the construction of the steam-boats employed 
upon the Tyne ?—Low pressure condensing engines. 
Are you aware of any reason which would render it expedient 
to forbid the use of high pressure engines on board steam-boats? 
—I look upon all engines, whether high pressure or low pressure, 
as dangerous to the passengers, unless due precaution be taken 
to emit the steam when exceeding a given pressure ; for in low 
pressure engines the boilers are always liable to burst or to alter 
their form, when the pressure becomes superior to the resistance ; 
all boilers but those that are cylindrical in the section, and with 
hemispherieal ends or portions of spheres or cones or conoids, 
are liable to alter the form by the natural expansive force of the 
steam, and therefore all boilers but of those forms owe their 
safety to their weakness; because if weak they will alter their 
form without danger, and if strong, they have been known to 
bend the iron so abruptly as to break asunder. 
Are you speaking of wrought, or cast iron ?—I speak of wrought 
iron; and consequently they explode, and in many instances have 
destroyed several of the passengers; they are so far more dan-~ 
gerous to the passengers that they frequently scald them, and do 
not actually kill them. There are a description of engines in use 
in the counties of Durham, Northumberland, Cumberland, and 
York, that are termed loco-motive engines; the form of their 
boilers is cylindrical, with curved ends. 
Are those applicable to boats?— Certainly; they are high 
pressure engines working with a force of from fifty to sixty-five 
pounds per inch; and no accident has happened to any of them 
but to one, the safety valve of which was stopped by a man sitting 
upon it or holding it down purposely; he said, “ We will have a 
good start and surprise them, we will go off so well ;’—the con- 
sequence was, that the boiler blew up and killed and weunded a 
very considerable number of people; I believe to the extent of 
forty-five, but I am not certain. 
Was that a cast- or a wrought-iron boiler ?—It was wrought: 
jron. * 
Can you suggest the means by which a high pressure engine 
can he rendered safe on board a vessel ?—It can only be rendered 
safe by having the form of the boiler, such as I have described, 
and the cylindric part of a limited diameter, with a competent 
thickness of wrought metal, either iron or copper, and the plates 
secured to each other by a double line of rivets; it is also re- 
quisite that there should be two safety-valves, each laden with 
any determinate weight per superficial inch of the narrowest part 
of the seat of the valye; one of those valves should be at a 
‘ iberty 
