Among the Forces | Page 7

other
bar, and away they go by gravity to the other end. Draw them up one
more incline, and they are ready to take a new load and buzz down to
the bottom again.
I have been riding round the glorious mountain sides in a horseless,
steamless, electricityless carriage, and been delighted to find hundreds
of tons of coal shooting over my head at the crossings of the X, and
both cars were drawn in opposite directions by the same force of

gravity in the heart of the earth.
If you do not take off your hat and cheer for the superb force of
gravitation, the wind is very apt to take it off for you.

THE FAIRY DRAWS GREATER LOADS
Pittsburg has 5,000,000 tons of coal every year that it wishes to send
South, much of it as far as New Orleans--2,050 miles. What force is
sufficient for moving such great mountains so far? Any boy may find
it.
Tie a stone to the end of a string, whirl it around the finger and feel it
pull. How much is the pull? That depends on the weight of the stone,
the length of the string, and the swiftness of the whirl. In the case of
David's sling it pulled away hard enough to crash into the head of
Goliath. Suppose the stone to be as big as the earth (8,000 miles in
diameter), the length of the string to be its distance from the sun
(92,500,000 miles), and the swiftness of flight the speed of the earth in
its orbit (1,000 miles a minute). The pull represents the power of
gravitation that holds the earth to the sun.
If we use steel wires instead of gravitation for this purpose, each strong
enough to support half a score of people (1,500 pounds), how many
would it take? We would need to distribute them over the whole earth:
from pole to pole, from side to side, over all the land and sea. Then
they would need to be so near together that a mouse could not run
around among them.
Here is a measureless power. Can it be gotten to take Pittsburgh coal to
New Orleans? Certainly; it was made to serve man. So the coal is put
on great flatboats, 36 x 176 feet, a thousand tons to a boat, and
gravitation takes the mighty burden down the long toboggan slide of
the Ohio and Mississippi Rivers to the journey's end. How easy!
[Illustration: The Head of the Toboggan Slide.]

One load sent down was 43,000 tons. The flatboats were lashed
together as one solid boat covering six and one half acres, more space
than a whole block of houses in a city, with one little steamboat to steer.
There is always plenty of power; just belt on for anything you want
done. This is only one thing that gravitation does for man on these
rivers. And there are many rivers. They serve the savage on his log and
the scientist in his palace steamer with equal readiness.

THE FAIRY WORKS A PUMP HANDLE
The Slave of the Ring could take Aladdin into a cave of wealth, and by
speaking the words, "Open Sesame," Ali Baba was admitted into the
cave that held the treasures of the forty thieves. But that is very little. I
have just come from a cave in Virginia City, Nev., from which men
took $120,000,000.
In following the veins of silver the miners went down 3,500 feet--more
than three fifths of a mile. There it was fearfully hot, but the main
trouble was water. They had dug a deep, deep well. How could they get
the water out? Pumps were of no use. A column of water one foot
square of that height weighs 218,242 pounds. Who could work the
other end of the pump handle?
They thought of evaporating the water and sending it up as steam. But
it was found that it would take an incredible amount of coal. They
thought of separating it into oxygen and hydrogen, and then its own
lightness would carry it up very quickly. But they had no power that
would resolve even quarts into their ultimate elements, where tons
would be required.
So they asked gravitation to help them. It readily offered to do so. It
could not let go its hold of the water in the mine, nor anywhere else, for
fear everything would go to pieces, but it offered to overcome force
with greater force. So it sent the men twenty miles away in the
mountains to dig a ditch all the way to the mine, and then gravitation
brought water to a reservoir four hundred feet above the mouth of the

mine. Now a column of this water one foot square can be taken from