nts. He was hunting for
big theories, scientific theories, something he could not understand,
and didn't find them. He expected to find some bright scheme to prevent
a boiler from exploding, didn't notice the simple little statement,
"keep water in it," that was too commonplace to notice. He was looking
for cuts, diagrams, geometrical figures, theories for constructing
engines and boilers and all that sort of thing and didn't find them.
Hence "It is no trick to run an engine."

If this has been your idea of "Rough and Tumble Engineering" forget all
about your theory, and go back and read it over and remember the little
suggestions and don't expect this book to teach you how to build an
engine. We didn't start out to teach you anything of the kind. That is
a business of itself. A good engineer gets better money than the man
who builds them. Read it as if you wanted to know how to run an engine
and not how to build one.

Study the following questions and answers carefully. Don't learn them
like you would a piece of poetry, but study them, see if they are
practical; make yourself thoroughly acquainted with the rule for
measuring the horse-power of an engine; make yourself so familiar with
it that you could figure any engine without referring to the book. Don't
stop at this, learn to figure the heating surface in any boiler. It
will enable you to satisfy yourself whether you are working your boiler
or engine too hard or what it ought to be capable of doing.

SOME THINGS TO KNOW

Q. What is fire?
A. Fire is the rapid combustion or consuming of organic
matter.

Q. What is water?
A. Water is a compound of oxygen and hydrogen. In weight
88 9-I0 parts oxygen to II I-I0 hydrogen. It has its maximum
density at 39 degrees Fahr., changes to steam at 2I2 degrees,
and to ice at 32 degrees.

Q. What is smoke?
A. It is unconsumed carbon finely divided escaping into
open air.

Q. Is excessive smoke a waste of fuel?
A. Yes.

Q. How will you prevent it
A. Keep a thin fire, and admit cold air sufficient to insure
perfect combustion.

Q. What is low water as applied to a boiler?
A. It is when the water is insufficient to cover all parts
exposed to the flames.

Q. What is the first thing to do on discovering that you have
low water?
A. Pull out the fire.

Q. Would it be safe to open the safety valve at such time?
A. No.

Q. Why not?
A. It would relieve the pressure on the water which being