f 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.

A rotary snowplow slices off two feet of a ten-foot drift at each
revolution, and by centrifugal force flings it out of the cutting with
a speed that a hundred navvies or dagos cannot equal.

ONE PLANT HELP

A thousand acres of land on Cape Cod were once blown away. This wind
excavation was ten feet deep. It was not an extraordinary wind, but
extraordinary land. It was made of rock ground up into fine sand by
the waves on the shore.

In all the deserts of the world the wind blows the itinerant sand on
its far journeys. If the wind is moderate it heaps the sand up into
little hills, some of them six hundred feet high, around any
obstruction, and then blows the sand up the slanting face of the hill
and over the top, where it falls out of the wind on the leeward side.
In this way the hill is always traveling. In North Carolina hills
start inland, and travel right on, burying a house or farm if it be in
the way, but resurrecting it again on the other side as the hill goes
on. Anyone may see these hills at the south end of Lake Michigan, as
he approaches Chicago, west of San Francisco, all along up the Columbia
River