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 eye-piece should be drawn out about half
an inch beyond [Page 96] its usual focusing for distant objects. The
farther it is drawn, the nearer must we hold the screen for a