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 this higher reservoir down to the bottom of the mine and weigh 25,000 pounds more than a like column that comes from the bottom to the top. This extra 25,000 pounds is an extra force available to lift itself and the other water out of the deep well, and they turn the greater force into a pump and work it in the cylinder as if it were steam. It lifts not only the water that works the pump, but the other water also out of the mine by gravitation. So man gets the water out by pouring more water in.
THE HELP OF INERTIA
Since the time of David many boys have swung pebbles by a string, or sling, and felt the pull of what we call a centrifugal (center-fleeing) force. David utilized it to one good purpose. Goliath was greatly surprised; such a thing never entered his head before. Whether a stone or an idea enters one's head depends on the kind of head he has.
We utilize this force in many ways now. Some boys swing a pail of milk over their heads, and if swung fast enough the centrifugal force overcomes the force of gravitation, and the milk does not fall. That is not utilizing the force. It often terrorizes the careful mother, anxious for the safety of the milk.
But in the arts of practical life we do utilize this force, which is only inertia.
Once it took a long time for molasses to drain out of a hogshead of damp sugar. Now it is put into a great tub, with holes in the side, which is made to revolve rapidly, and the molasses flies out. In the best laundries clothes are not wrung out, to the great damage of tender fabrics, but are put into such a tub and whirled nearly dry. So fifty yards of woolen cloth just out of the dye vat--who could wring it? It is coiled in a tub called a wizard, and whirled.
Muddy water is put through a process called clarification. It is the same, except that there are no holes in the vessel. The heavier particles of dirt, that would settle in time, take the outside, leaving perfectly clean water in the middle. A perpendicular perforated pipe, with a faucet below, drains off all the clear water and leaves all the mud. Milk is brought in from the milking and put into a separator; whirl it, and the heavier milk takes the outside of the whirling mass, and the lighter cream can be drawn off from the middle. It is far more perfectly separated than by any skimming.