ly curbed, and
the planet held in its true curve about the sun. These giant worlds
must be perfectly handled. Their speed, amounting to seventy times
as fast as that of a rifle-ball, must be managed. Each and every
world may be said to be lifted momentarily and swung perpetually
at arm's-length by the power of the sun.

The sun warms us. It would convey but a small idea of the truth
to state how many hundreds of millions of cubic miles of ice could
be hailed at the sun every second without affecting its heat; but,
if any one has any curiosity to know, it is 287,200,000 cubic miles
of ice per second.

We journey through space which has a temperature of 200 deg. below
zero; but we live, as it were, in a conservatory, in the midst of
perpetual winter. We are roofed over by the air that treasures the
heat, floored under by strata both absorptive and retentive of heat,
[Page 95] and between the earth and air violets grow and grains
ripen. The sun has a strange chemical power. It kisses the cold
earth, and it blushes with flowers and matures the fruit and grain.
We are feeble creatures, and the sun gives us force. By it the light
winds move one-eighth of a mile an hour, the storm fifty miles, the
hurricane one hundred. The force is as the square of the velocity.
It is by means of the sun that the merchant's white-sailed ships are
blown safely home. So the sun carries off the miasma of the marsh,
the pollution of cities, and then sends the winds to wash and
cleanse themselves in the sea-spray. The water-falls of the earth
turn machinery, and make Lowells and Manchesters possible, because
the sun lifted all that water to the hills.

Intermingled with these currents of air are the currents of electric
power, all derived from the sun. These have shown their swiftness
and willingness to serve man. The sun's constant force displayed
on the earth is equal to 543,000,000,000 engines of 400-horse power
each, working day and night; and yet the earth receives only
1/21500000000 part of the whole force of the sun.

Besides all this, the sun, with provident care, has made and given
to us coal. This omnipotent worker has stored away in past ages
an inexhaustible reservoir of his power which man may easily mine
and direct, thus releasing himself from absorbing toil.

EXPERIMENTS.

Any one may see the spots on the sun who has a spy-glass. Darken
the room and put the glass through an opening toward the sun, as
shown in Fig. 37. The e