It may be supposed that there are few
People among us so ignorant, but must necessarily know of what value the Falls
of Water are in most Places, as being applicable to mills; which are made after
various kinds and forms, according to the different genius and abilities of the
mill right; for mill work being in manner infinitely diversified; and had I
leisure to comment there on, and give you an account,not only of the vast
variety that I have seen and heard of; but (when encouraged) what may yet
brought to work by steady stream, and the rotation or circular motion of a
water-wheel, it would swell these papers to a much larger volume than was at
first designed, and frustrate my intended brevity. I only just hint this to
show what use this Engine may be put to in working of mills, especially where
coals are cheap.
I have only this to urge, that water in its fall from any determinate height,
has simply a force answerable and equal to the force that raises it. So that an
engine which will raise as much water as two horses, working together at one
time in such a work, can do, and for which there must be constantly kept ten or
twelve horses for doing the same. Then I say, such an engine may be made large
enough to do the work required in employing eight, ten, fifteen, or twenty
horses to be constantly maintained and kept for doing such a work; it will be
improper to stint or confine its uses and operation in reflect of water-mills.
For the water. Be the mine never so deep, each engine working it 60, 70, or80
foot high by applying or setting the engines one over another, as shall be
showed at large hereafter in the following pages, you may by a sufficient
number of engines keep the bottom of any mine dry; and when once you know how
large your feeder or spring is, it is very easy to know what sized engine , or
what number of engines will do your business.
The coals used in this engine is of as little value, as the coals commonly
burned on the mouths of the coal-pits are: for an engine of a three inch-bore,
or the there about, working the water up 60 foot high, requires a fire-place of
not above twenty inches deep and about fourteen or fifteen inches wide, which
will occasion so small a consumption, that in a coal-pit it is of no account,
as we have experienced. And in all parts of England where there are mines;
coals are so cheap, that the charge of them is not to be mentioned when we
consider the vast quantity of water raised by the inconsiderable value of the
coals used and burnt in so small a furnace. What the quantity of coals used for
one engine in a year is, cannot easily be ascertained, because of the different
nature of the several sorts of coals.
As for the cure of damps by this engine, the air perpetually crowding into the
ash-hole and fire-place, as it is natural for it to do, and with a most
impetuous force discharge with the smoke at the top of the chimney, the
contiguous air is successively following it; so that not only all steams or
vapors whatsoever, that may or can arise, must naturally force its way through
the fire and so be discharged at the top with the smoke. But this motion of the
fire will occasion the fresh Air to descend from above, down all the pits, and
every where else in the mine, but down the chimney; provided you have a heading
drift, or passage from all the shafts, or pits inin the same work it matters
not; for here will be a perpetual circulation of air, andwith that swiftness,
as is hardly to be believed. This I have tried, and know to be true; so leave
the ingenious miner to his own judgment. Whether when all the air is in a swift
motion, that any stagnation of air (which has always been adjudged the cause of
damps) can happen in any pit.