to a
hopper and borne to the gins below by means of traveling racks."

"How many gins are there to a factory?" questioned Mary.

"That depends on the size of the factory and the amount of work brought
there to be done," was the reply. "A fair-sized factory in a busy
district will have half-a-dozen gins or more; and when you know that
one gin will clean from three hundred to three hundred and fifty pounds
of cotton an hour you will see that it will take a pretty big supply to
keep such a lot of machinery moving. There is a separate hopper for
each gin and if the supply fed into it comes too fast it can be stopped
and switched to other gins. Once in the clutch of the relentless knives
the cotton is shredded apart and the seeds drop out and fall into a
traveling basket. From this basket they are forced through a tube to an
oil mill which usually stands in another part of the grounds."

"Cottonseed oil!" murmured Mary, recognizing an old friend. "We often
use it to fry things. It's good on lettuce, too. But somehow I never
thought that it was really made from the seeds of cotton."

"We often accept terms without thinking much about them, don't we?"
Captain Dillingham agreed. "But cottonseed oil is a genuine by-product
of cotton."

"What is a by-product?" smiled Mary ingenuously.

"A by-product is something made from the leavings," put in Carl without
hesitation. "Hash is a by-product of corned beef."

A laugh greeted the assertion.

"Technically speaking a by-product is something that is turned to
account from what would otherwise have been waste. Every person who
manufactures on a large scale tries to think what he can do with what
is left after he has made the thing he started out to make. This he
does for two reasons: first he wishes to turn back into money every
ounce of material for which he has paid; secondly he desires to get rid
of stuff which would otherwise accumulate and (if not combustible)
force him into the added expense of carting it away. In other words he
seeks to convert his waste into an asset instead of a liability.
Therefore all big producers tax their brains to invent things that can
be made from their waste, and such commodities are called by-products.
Many of these things require no ingenuity for frequently they are
articles much needed in other trades. Masons, for example, are only too
thankful to have the hair taken from tanned leather to hold their
plaster together; and those who dry and