and yet you know and
I know that very much higher pressure is being carried wherever the
traction engine is used, and I want to say that a very high pressure is
no gauge or guarantee of the intelligence of the engineer. The less a
reckless individual knows about steam the higher pressure he will carry.
A good engineer is never afraid of his engine without a good reason, and
then he refuses to run it. He knows something of the enormous pressure
in the boiler, while the reckless fellow never thinks of any pressure
beyond the I00 or I40 pounds that his gauge shows. He says, "'O!
That,' that aint much of a pressure, that boiler is good for 200
pounds." It has never dawned on his mind (if he has one) that that I40
pounds mean I40 pounds on every square inch in that boiler shell, and
I40 on each square inch of tube sheets. Not only this but every square
inch in the shell is subjected to two times this pressure as the boiler
has two sides or in other words, each square inch has a corresponding
opposite square inch, and the seam of shell must sustain this pressure,
and as a single riveted boiler only affords 62 per cent of the strength
of solid iron.
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