Scientists used to say that what we call nature,
that is the whole universe, was made up of matter and force; but nowadays they
find that the atoms that make up the matter are really force, so that matter
itself is only a form of force. But it will be convenient to see the lord force
in its usual sense of energy, and to give as: illustration of the forces of
nature such great powers as light, heat. Electrical. Gravitation and life.
The study of the first four of these forces is
called the scenic of Physics; and Physicists have discovered a great deal about
then. But we can only speak here of a few of the more obvious effects of these
forces, especially as far as they have been found useful to man.
Take the force of gravitation. The effect of
gravitation is one of the most familiar experiences in everyday life, as we
know when we fall down, and when we see anything that is thrown into the air fall-back
again to the earth. Yet no one knows exactly what this force is. Isaac Newton. The
great English mathematician discovered the law of gravitation -- that is the
rule by which this force always seems to work: but even he could not explain
what it really is. All he could say was that if seemed to be force of attraction
that tends to drawn masses of matter towards each other in a certain way,
namely in direct proportion to their mass and in inverse proportion to the
square of their distance. Hence the earth on which we live draws all smaller
objects near it towards its centre. So that as we sax everything tends to fall
onto the earth: hence the sun toward the earth towards itself. And keeps it resolving
round it. But for gravitation. All the things of the surface of the earth would
be flung off the earth itself would fall to pieces. And rush off Tin fragments
into space.
Men have always been familiar with lightning: but
it is only in modem times that they have identified it with electricity, and found
ways of producing it and making it useful to them, in such forms as the
telegraph, telephone and wireless. And harnessed it to drive engines and
tram-cars, and to give them light and heat. In fact it is now supposed that
solid matter itself is really a form of electricity, because the atoms of
matter are composed of electrons. This is really electrical energy.
Times fails to speak of light and heat. Expect to
say that without them the most wonderful and mysterious force of all, namely
life, would be impossible. Biologists can tell us a lot about vying organisms
-- plants and animals -- but no one can tell us exactly what life is. All we
known is that it is the force of life that make the seed grow into a great
tree, and the tiny baby in a strong man; and that enables plants and animals to
produce other Waving plants and animals.