lve, which it will
force open, and drive out the mixture of air and steam, till all the air
will have passed from the vessel, and nothing but the vapour of water
remain. This done, a cock is opened, and the water from the cistern is
allowed to flow over the outside of the steam vessel, first having
stopped the further supply of steam from it; this produced the
immediate condensation of the steam contained in it, by the temperature
being brought down again by the cold water, and the condensation thus
produced caused a vacuum inside the vessel. The valve will then be kept
closed by the atmosphere outside, and the pressure of the air on the
surface of the water in the well or reservoir will open another valve,
force the water up the pipe, till, after one or two exhaustions--if I
may so term it--it will at last reach the second vessel. Thus far the
atmosphere has done all the work, but at last the water fills the
vessel, and then comes the forcing point. Now the power of the steam
itself is used to drive the water up the pipe. The steam is again let
into the vessel, now filled in whole, or at least in great part, with
water; at first it will, as before, condense rapidly, but soon the
surface of the water will get heated, and as hot water is lighter than
cold, it will keep on the surface, and the pressure of the steam from
the boiler will drive all the water from the vessel up the pipe. When it
is empty the cock is again opened, and the steam, which the vessel by
this time only contains, is again condensed, and the same process which
I have just described is again commenced and carried out, thus making
Savory's engine a complete pump by the aid of the vapour of water as
raised by fire.

Savory had the honour of showing this engine to His Majesty William III.
at Hampton Court Palace, and to the Royal Society. He proposed the
following uses, which perhaps may as well be mentioned, as they show how
little was then known of the real value of the power of steam:--1. To
raise water to drive mill-wheels--fancy erecting a steam engine now, of
say fifty horse-power, to raise water to turn a wheel of say thirty; 2.
To supply palaces and houses with water; 3. Towns with water; 4.
Draining marshes; 5. Ships; 6. Draining mines. There is one more thing I
may mention as curious, that though the steam he used must have been of
a high pressure, he did not use a safety-valve, though it had been
invented about the year 1681 by Papin. The consu