Counter-Sun and Planet Wheel-Fly and other Modes of regulating Velocity-Boiler-Safety-valves-Furnace 123

CHAPTER VI.

Savery's Engine improved by Pontifex-Atmospheric Engine-Single-acting Engine, by Boulton and WattMurray and Wood's Engine-High-pressure EngineWoolf's Double-cylinder Expansion Engine-Maudslay's Portable Engine-Masterman's Rotatory Engine-Smokeconsuming Furnaces

APPENDIX.

(A)

145

List of Patents for the Steam Engine, with an Analytical Account of those more immediately connected with its Improvement and general Application to the useful Arts .. 1

(B)

Abstract of Evidence and Reports made by a Select Committee of the House of Commons, on Steam Engines and Furnaces..

(C)

44

Chronological Catalogue of Works descriptive of the Steam Engine...

82

HISTORICAL ACCOUNT

OF THE

STEAM ENGINE.

CHAP. I.

Nature of Steam-Application of it as a moving power-Brancas-Marquis of Worcester-Sir Samuel Morland-Papin-Savery-NewcomenHulls Falck-Amontons-Deslandes-Francois.

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As the whole power of the Steam Engine depends on the employment of elastic vapour, produced from water at different temperatures, varying from 212°, or the boiling point of Fahrenheit's thermometer, to 300° of the same scale, it may be advisable in the first instance to examine some of the principal phenomena connected with the formation of vapour in its most simple form, and its application to the steam engine will then be sufficiently obvious.

B

close vessel, and afterwards produce a vacuum by condensation, no more heat is necessary than what will raise the water for this purpose to 212°; but if, on the contrary, high pressure steam is required, a very considerable increase of heat will be essential; and of this kind was the elastic vapour employed in all the early steam engines to which we may now more immediately direct the reader's attention.

Among the numerous competitors for the honour of having first suggested steam as a moving power in mechanics, we must certainly place Brancas and the Marquis of Worcester in the foremost rank. The former of these was an Italian philosopher, of considerable eminence, and who, in 1629, published a treatise entitled, "Le Machine, &c." which contained a description of a machine

for this purpose. The apparatus employed by

Brancas, was in fact nothing more than a large æolipile, similar to the blow-pipe invented by M. Pictet of Geneva, with this difference, that the aperture in the pipe connected with the body of the æolipile instead of being directed to the lamp, (or in this case, the furnace that heated the machine,) was made to strike against the floats or vanes of a wheel, by which means a rotatory motion was produced.

After the publication of this scheme, which it is probable was never put in practice with any useful effect, nearly thirty years elapsed ere the farther consideration of this important subject

pand to about five, ten, twenty, thirty, and forty times its volume respectively; its elastic force, when thus dilated, being in each case equal to the ordinary pressure of the atmosphere.

One pound of Newcastle coal converts seven pounds of boiling water into steam; and the time required to convert a given quantity of boiling water into steam, is six times that required to raise it from the freezing to the boiling point.

To shew by direct experiment the great expansive force of vapour from water when converted into steam, by the application of heat, it will only be necessary to take a glass tube, at one end of which is a bulb of two inches in diameter, and dropping into it a single spherule of water, the diameter of which will scarcely exceed one tenth of an inch, or about the eighteen hundredth part of the size of the glass bulb, we shall find, that it may very readily be expanded by the application of heat, so as to expel the air from the vessel. That this is actually the case, may be shewn by merely plunging the mouth of the tube into cold water, and suffering the steam to return to its original state, which being effected by the abstraction of a portion of its artificial heat, the water will rush in from the external vessel, and occupy the place of the steam thus condensed, which could not have taken place had any portion of the air remained in the tube or its bulb.

From these data, it will be evident, that when steam is merely employed to displace the air in a

Tower of London, was preparing some food on the fire of his apartment, and the cover having been closely fitted, was, by the expansion of the steam, suddenly forced off and driven up the chimney. This circumstance attracting his attention, led him to a train of thought, which terminated in this important discovery. But no figure has been preserved of his invention; nor, as we have good reason to suppose, any description of the machine he employed, except the sixty-eighth article in the above-mentioned work. We shall content ourselves, therefore, with extracting that article from the noble author's MS. preserved in the British Museum.

"An admirable and most forcible way to drive up water by fire; not by drawing or sucking it upwards, for that must be as the philosophers call it, infra sphæram activitatis, which is but at such a distance. But this way hath no boundary, if the vessels be strong enough; for I have taken a piece of a whole cannon, whereof the end was burst, and filled it three quarters full of water, stopping and screwing up the broken end, as also the touch-hole; and making a constant fire under it, within twenty-four hours it burst, and made a great crack; so that having found a way to make my vessels, so that they are strengthened by the

properties of the above engine; and it is certain that he never published any key to the first hint furnished in the Century of Inventions,