1. I shall endeavour in this course of lectures to illustrate the
elementary laws of mechanics by means of experiments. In order to
understand the subject treated in this manner, you need not possess
any mathematical knowledge beyond an acquaintance with the rudiments
of algebra and with a few geometrical terms and principles. But even
to those who, having an acquaintance with mathematics, have by its
means acquired a knowledge of mechanics, experimental illustrations may
still be useful. By actually seeing the truth of results with which you
are theoretically familiar, clearer conceptions may be produced, and
perhaps new lines of thought opened up. Besides, many of the mechanical
principles which lie rather beyond the scope of elementary works on
the subject are very susceptible of being treated experimentally; and
to the consideration of these some of the lectures of this course will
be devoted.
Many of our illustrations will be designedly drawn from very
commonplace sources: by this means I would try to impress upon you that
mechanics is not a science that exists in books merely, but that it is
a study of those principles which are constantly in action about us.
Our own bodies, our houses, our vehicles, all the implements and tools
which are in daily use—in fact all objects, natural and artificial,
contain illustrations of mechanical principles. You should acquire the
habit of carefully studying the various mechanical contrivances which
may chance to come before your notice. Examine the action of a crane
raising weights, of a canal boat descending through a lock. Notice the
way a roof is made, or how it is that a bridge can sustain its load.
Even a well-constructed farm-gate, with its posts and hinges, will give
you admirable illustrations of the mechanical principles of framework.
Take some opportunity of examining the parts of a clock, of a
sewing-machine, and of a lock and key; visit a saw-mill, and ascertain
the action of all the machines you see there; try to familiarize
yourself with the principles of the tools which are to be found in any
workshop. A vast deal of interesting and useful knowledge is to be
acquired in this way.