is, though it is invisible to us. Most children have this
glorious gift, and love to picture to themselves all that is told
them, and to hear the same tale over and over again till they see
every bit of it as if it were real. This is why they are sure to
love science it its tales are told them aright; and I, for one,
hope the day may never come when we may lose that childish
clearness of vision, which enables us through the temporal things
which are seen, to realize those eternal truths which are unseen.

If you have this gift of imagination come with me, and in these
lectures we will look for the invisible fairies of nature.

Watch a shower of rain. Where do the drops come from? and why
are they round, or rather slightly oval? In our fourth lecture
we shall se that the little particles of water of which the
raindrops are made, were held apart and invisible in the air by
heat, one of the most wonderful of our forces* or fairies, till
the cold wind passed by and chilled the air. Then, when there
was no longer so much heat, another invisible force, cohesion,
which is always ready and waiting, seized on the tiny particles
at once, and locked them together in a drop, the closest form in
which they could lie. Then as the drops became larger and larger
they fell into the grasp of another invisible force, gravitation,
which dragged them down to the earth, drop by drop, till they
made a shower of rain. Pause for a moment and think. You have
surely heard of gravitation, by which the sun holds the earth and
the planets, and keeps them moving round him in regular order?
Well, it is this same gravitation which is a t work also whenever
a shower of rain falls to the earth. Who can say that he is not
a great invisible giant, always silently and invisibly toiling in