held it was not strong enough to carry a greater weight.
Mr. Worthington has carefully drawn on a magnified scale the exact shape
of a drop of water of different sizes, and these you now see upon the
diagram on the wall (Fig. 2). These diagrams will probably suggest the
idea that the water is hanging suspended in an elastic bag, and that the
bag breaks or is torn away when there is too great a weight for it to
carry. It is true there is no bag at all really, but yet the drops take
a shape which suggests an elastic bag. To show you that this is no
fancy, I have supported by a tripod a large ring of wood over which a
thin sheet of india-rubber has been stretched, and now on allowing water
to pour in from this pipe you will see the rubber slowly stretching
under the increasing weight, and, what I especially want you to notice,
it always assumes a form like those on the diagram. As the weight of
water increases the bag stretches, and now that there is about a pailful
of water in it, it is getting to a state which indicates that it cannot
last much longer; it is like the water-drop just before it falls away,
and now suddenly it changes its shape (Fig. 3), and it would immediately
tear itself away if it were not for the fact that india-rubber does not
stretch indefinitely; after a time it gets tight and will withstand a
greater pull without giving way. You therefore see the great drop now
permanently hanging which is almost exactly the same in shape as the
water-drop at the point of rupture. I shall now let the water run out by
means of a syphon, and then the drop slowly contracts again. Now in this
case we clearly have a heavy liquid in an elastic bag, whereas in the
drop of water we have the same liquid but no bag that is visible. As the
two drops behave in almost exactly the same way, we should naturally be
led to expect that their form and movements are due to the same cause,
and that the small water-drop has something holding it together like the
india-rubber you now see.

[Illustration: Fig. 2.]

[Illustration: Fig. 3.]

Let us see how this fits the first experiment with the brush. That
showed that the hairs do not cling together simply because they are wet;
it is necessary also that the brush should be taken out of the water, or
in other words it is necessary that the surface or the skin of the water
should be present to bind the hairs together. If then we suppose that
the surface of water is like an elastic skin, t