Chap. VIII.

BRITAIN.

581

Steam Engine. — The application of steam to draining, mining, manufactures, machinery,railroads, and navigation has so changed the labours of the civil engineer, that it isnecessary to notice, however briefly, its inventors and progress.

Windmills arc no longer employed to exhaust the water from our fens, nor are the rudeconstructions of complicated machinery under our bridges now required to throw upwater to our houses. The miner is enabled to penetrate to greater depths in the bowels ofthe earth in search of the ore, and the civil engineer has an efficient agent on all occasionswhere great power is required; in the various operations of pile-driving, exhausting water,dredging and cleansing the bottoms of rivers or harbours, moving weights, and in con-structions, it is equally important, and thus new elements have been introduced into hisemployment since the days of Perronet and Smeaton .

It is not necessary to give a detail of the various opinions relative to the invention of thesteam engine; in the history of the progress of the useful arts none has been more keenlycontested : different nations, as well as individuals, have put in their claims; but theefficacy of this useful machine depends on several physical properties, and on a variety ofmechanical arrangements, to render them available; and suppose these all to have beenknown in the early age of science, they were not combined until James Watt devoted hismind to the subject: previous to this period, the steam engine possessed extremely limitedpower, and was inferior to other mechanical contrivances as a prime mover : but since hisgenius matured it, it has become the source of wealth to the British nation, as well asbeneficial to the progress of civilisation and the comfort of the whole human race, and a mo-nument to his fame. It must be evident that the engine as it now exists is not the exclusiveinvention of one individual, but the result of discoveries made during the two previouscenturies : its progress from its commencement is a curious history, attesting the slowworking of the human mind, and how long a period often intervenes before the geniussprings up who can mature and render useful the so-called dreams of philosophers.

It is difficult to assign a time when the properties of steam first attracted attention;as early as 130 years before Christ we find some mention in the writings of Hero ofAlexandria of a philosophical toy, called an a?olipile, the principle of which was nearlythe same as that which produces the motion in Barker’s mill; in America , a few yearsago, an engine was constructed of 21-horse power upon this system, and its only faultwas stated to be the consuming too much fuel. This kind of engine was first made byMr. Avery.

At the commencement of the seventeenth century Baptists Porta, who invented thecamera obscura, gives in a commentary on the Pneumatica of Hero the design for a steamfountain, which raised water in a similar way to the steam-engine, the steam being formedin a separate vessel from that which contained the water to be raised.

A tube introduced the steam into the cistern, which was nearly filled with water, theend of the tube being above the level of the water; the steam occupied the space above thewater, and by its elastic power forced the water through the bent tube.

Solomon de Caus, an engineer and architect in the employment of Louis XIII. of France,showed that water might be raised by the aid of fire higher than its own level; his publi-cation is said to be the first instance in which steam is mentioned as a moving power.

In a copper ball, well soldered together, was a vent-hole, through which the water alsoentered, and a perpendicular tube, which approached nearly to the bottom of the ball,and was carefully soldered in. The ball, filled with water, and placed upon the fire, soonformed a quantity of steam, which having no escape pressed on the surface of the water,and occasioned it to mount in the perpendicular tube.

Giovanni Branca , an Italian engineer , formed a steam windmill, which seems to be oneof the first instances of an attempt to render this power practically useful; and in a workpublished about 1629, there is a representation of this invention. It consists of a boilerwith a spout directed towards a horizontal wheel, and the steam which issues from itis made to strike against the flat vanes or floats contrived on its circumference, pro-ducing a rotary motion in the wheel, which he proposed to transmit to machinery thatshould raise buckets, grind corn, &c. The specific gravity of steam being low, no greatpower could have been obtained by it when so applied; and being so rapidly condensed,and so much resisted by the air, which is twice its weight, its force could not be great.

Edward Somerset , Marquis of Worcester , who was confined in the Tower for being im-plicated in a plot at the time of the Stuarts, one day observing the lid of the pot in whichhis dinner was cooked suddenly fly off, asked his attendant, “ What is to be done in sucha melancholy den, unless we have the liberty of thought?” and probably this circumstance,trifling as it may appear, gave rise to his consideration of steam as a convenient motivepower. In his Century of Invention , published in 1663, he shows “ an admirable andmost forcible way to drive up water by fire, not by drawing or sucking it upwards, forthat must be, as the philosopher calleth it, * intra sphaerum activitatis,’ which is but at such adistance. But this way hath no bounder if the vessel be strong enough; for I have takena piece of a whole cannon whereof the end was burst, and filled it three quarters full of

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