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 consumption of fuel was enormous in Savory’s engine, as may easily be perceived from the great loss of steam by condensation.  Nevertheless, it was on the whole a good and a workable engine, as we find the following said of it by Mr. Farey:—­“When comparison is made between Captain Savory’s engine and those of his predecessors, the result will be favourable to him as an inventor and practical engineer.  All the details of his invention are made out in a masterly style, so as to make it a real workable engine.  His predecessors, the Marquis of Worcester, Sir S. Morland, Papin, and others, only produced outlines which required to be filled up to make them workable.”