le on the wall, where it comes to a
focus. If the mirror on the table were plane, the whole movement of
the light would be only about eight inches, but the mirror is convex,
and this magnifies the motion nearly eight times. At the present
moment the attracting weights are in one extreme position, and the
line of light is quiet. I will now move them to the other position,
and you will see the result--the light slowly begins to move, and
slowly increases in movement. In forty seconds it will have acquired
its highest velocity, and in forty more it will have stopped at 5
feet 81/2 inches from the starting point, after which it will slowly
move back again, oscillating about its new position of rest.

It is not possible at this hour to enter into any calculations; I will
only say that the motion you have seen is the effect of a force of
less than one ten-millionth of the weight of a grain, and that with
this apparatus I can detect a force two thousand times smaller still.
There would be no difficulty even in showing the attraction between
two No. 5 shot.

And now, in conclusion, I would only say that if there is anything
that is good in the experiments to which I have this evening directed
your attention, experiments conducted largely with sticks, and string,
and straw and sealing wax, I may perhaps be pardoned if I express my
conviction that in these days we are too apt to depart from the simple
ways of our fathers, and instead of following them, to fall down and
worship the brazen image which the instrument maker hath set up.

* * * * *

NATURE, COMPOSITION, AND TREATMENT OF ANIMAL AND VEGETABLE FABRICS.

The inseparable duties of studying the composition of the various
animal and vegetable fabrics, as also their nature--when in contact
with the various mineral, vegetable, animal, and gaseous bodies
applied in the individual industries--should not devolve upon the
heads, chemists, or managers of firms alone. It is most important that
every intelligent workman, whom we cannot expect to acquire a very
extensive knowledge of chemistry and perfect acquaintance of the
particular nature and component parts of fabrics, should, at least, be
able to thwart the possibility of the majority of accidents brought
about in regard to the quality and aspect of materials treated by
them.

In the treatment of wool the first operations are of no mean
importance, and the whole subsequent operations