illustrative experiment, and the more familiar they are to the
student, the more thoroughly is he likely to acquire the idea which it
is meant to illustrate. The educational value of such experiments is
often inversely proportional to the complexity of the apparatus. The
student who uses home-made apparatus, which is always going wrong,
often learns more than one who has the use of carefully adjusted
instruments, to which he is apt to trust, and which he dares not take
to pieces.

It is very necessary that those who are trying to learn from books the
facts of physical science should be enabled by the help of a few
illustrative experiments to recognise these facts when they meet with
them out of doors. Science appears to us with a very different aspect
after we have found out that it is not in lecture rooms only, and by
means of the electric light projected on a screen, that we may witness
physical phenomena, but that we may find illustrations of the highest
doctrines of science in games and gymnastics, in travelling by land
and by water, in storms of the air and of the sea, and wherever there
is matter in motion.

This habit of recognising principles amid the endless variety of their
action can never degrade our sense of the sublimity of nature, or mar
our enjoyment of its beauty. On the contrary, it tends to rescue our
scientific ideas from that vague condition in which we too often leave
them, buried among the other products of a lazy credulity, and to
raise them into their proper position among the doctrines in which our
faith is so assured, that we are ready at all times to act on them.

Experiments of illustration may be of very different kinds. Some may
be adaptations of the commonest operations of ordinary life, others