Lecture ii Sunbeams and How They Work
Who does not love the sunbeams, and feel brighter
and merrier as he watches them playing on the wall,
sparkling like diamonds on the ripples of the sea,
or making bows of coloured light on the waterfall?
Is not the sunbeam so dear to us that it has become
a household word for all that is merry and gay? and
when we want to describe the dearest, busiest little
sprite amongst us, who wakes a smile on all faces
wherever she goes, do we not call her the “sunbeam
of the house”?
And yet how little even the wisest among us know about
the nature and work of these bright messengers of
the sun as they dart across space!
Did you ever wake quite early in the morning, when
it was pitch-dark and you could see nothing, not
even your own hand; and then lie watching as time
went on till the light came gradually creeping in
at the window? If you have done this you will
have noticed that you can at first only just distinguish
the dim outline of the furniture; then you can tell
the difference between the white cloth on the table
and the dark wardrobe beside it; then by degrees all
the smaller details, the handles of the drawer, the
pattern on the wall, and the different colours of all
the objects in the room become clearer and clearer
till at last you see all distinctly in broad daylight.
What has been happening here? and why have the things
in the room become visible by such slow degrees?
We say that the sun is rising, but we know very well
that it is not the sun which moves, but that our earth
has been turning slowly round, and bringing the little
spot on which we live face to face with the great
fiery ball, so that his beams can fall upon us.
Take a small globe, and stick a piece of black plaster
over England, then let a lighted lamp represent the
sun, and turn the globe slowly, so that the spot creeps
round from the dark side away from the lamp, until
it catches, first the rays which pass along the side
of the globe, then the more direct rays, and at last
stands fully in the blaze of the light. Just
this was happening to our spot of the world as you
lay in bed and saw the light appear; and we have to
learn today what those beams are which fall upon us
and what they do for us.
First we must learn something about the sun itself,
since it is the starting-place of all the sunbeams.
If the sun were a dark mass instead of a fiery one
we should have none of these bright cheering messengers,
and though we were turned face to face with him every
day we should remain in one cold eternal night.
Now you will remember we mentioned in the last lecture
that it is heat which shakes apart the little atoms
of water and makes them gloat up in the air to fall
again as rain; and that if the day is cold they fall
as snow, and all the water is turned into ice.
But if the sun were altogether dark, think how bitterly
