STEAM-ENGINES.
The Steam-Engine is one of the most important of human discoveries, and is certainly one of those which afford the greatest portion of ease and advantage to the human species, as well in the operation of its cause, as in its ultimate effects. The most powerful of machines had its origin from the single idea of one individual of our own nation. It has been, from time to time, improved by different individuals, also natives of Britain, the precise period of which improvements can be traced, and their effects fortunately ascertained.
Although we should observe, that the first principle of this mechanical power was discovered by some of the ancient nations, many ages before that which gave the origin to the present practised invention, but from the state of information, it is conceived, to answer no purpose of utility. It may be said to have occurred in a small machine which the ancients called an Æolipila (the bull of Æolus) consisting of a hollow ball of metal, with a slender neck, or pipe, also of metal, having a small orifice entering into the ball, by means of a screw; this pipe being taken out, the ball being filled with water, and the pipe again screwed in, the ball is heated—there issues from the orifice, when sufficiently hot, a vapour, with great violence and noise; care was required that this should not be by accident stopped, if it were, the machine would infallibly burst, and perhaps, to the danger of the lives of all in its vicinity, so immense is its power.
Another way of introducing the water was first to heat the ball when empty, and then suddenly to immerse it in water. Descartes, in particular, has used this instrument to account for the natural generation of winds. Chauvin thinks it might be employed instead of bellows, to blow a fire. It would admirably serve to fumigate a room, being filled with perfume instead of common water. It is said to have been applied to clear chimneys of their soot, a practice still alleged to be common in Italy. Dr. Plott, in his “History of Staffordshire,” records this singular custom, where the Æolipila is used to blow the fire. “The lord of the mannor of Essington is bound by his tenure to drive a goose, every New Year’s day, three times round the hall of the Lord of Hilton, while Jack of Hilton, a brazen Æolipila, blows the fire.” The last circumstance we shall mention of this instrument, has relation to an antique one, discovered whilst digging the Basingstoke canal, representing a grotesque metallic figure, in which the blast proceeded from the mouth. This figure is now in the possession of the Society of Antiquaries of London. In this instrument, the uncommon elastic force of steam was recognised before the suggestion of the Marquis of Worcester, which follows:
“In 1655, or subsequent thereto, the Marquis of Worcester published the earliest account of the application of this power for the purposes of utility, and suggested it as applicable to raising water. ‘Sixty-eight. An admirable and most forcible way to drive up water by fire; not by drawing or sucking it upwards, for that would be what the philosopher calleth it, intra spherum actroctatis, which is, but at such a distance. But this way has no bounder, if the vessel be strong enough; for I have taken a whole piece of cannon, whereof the end was burst, 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 a way to make my vessels, so that they are strengthened by the force within them, and the one to fill after the other, I have seen the water run like a constant fountain stream, forty feet high; one vessel of cold water being consumed, another begins to force and refill with cold water, and so successively; the fire being tended and kept constant, which the self-same person may likewise abundantly perform, in the interim between the necessity of turning the cocks.’”
The marquis’s ingenuity did not, it appears, meet with that attention which it deserved, from those to whom his communication was addressed. In the article of steam it has been since very much improved, and is acted upon for the most useful of purposes; also his ideas for short-hand telegraphs, floating baths, escutcheons for locks, moulds for candles, and a mode to disengage horses from a carriage, after they have taken fright; which, with several others, proclaim the originality and ingenuity of the mind of this nobleman—an honour which very few of the British nobility aspire to.
Since his time, another design upon the same principle has been projected by Captain Thomas Savery, a commissioner of sick and wounded, who in the year 1691 obtained a patent for “a new invention for raising water, and occasioning motion to all sorts of mill-work, by the impellant force of fire.” This patent bears date the 25th of July, sixteenth of William III., A. D. 1698. The patent states that the invention will be of great use for drawing of mines, serving towns with water, and working all sorts of mills. “Mr. Savery, June 14th, 1699, entertained the Royal Society with showing a model of his engine for raising water by help of fire, which he set to work before them; the experiment succeeded according to expectation.”
The above memoir is accompanied with a copperplate figure, with references by way of description; from whence it appears, that the engine then shown by Captain Savery was for raising water, not only by the expansive force of steam, like the Marquis of Worcester’s, but also by the condensation of steam, the water being raised by the pressure of a rarified atmosphere to a given height, by the expansive force of steam, in the same manner as the Marquis proposed. This action was performed alternately in two receivers, so that while the vacuum formed in one was drawing up water from the well, the pressure of steam in the other was forcing up water into the reservoir; but both receivers being supplied by one suction-pipe and one forcing-pipe, the engine could be made to keep a continual stream, so as to suffer very little interruption. This engine of Captain Savery’s displays much ingenuity, and is almost as perfect in its contrivance as the same engine has been made since his time. We regret, that without a figure we cannot supply a perfect description of it.
However, it appears that it was necessary to have two boilers, or vessels of copper, one large and the other smaller: those boilers have a gauge-pipe inserted into the smaller boiler, within about eight inches of its bottom, and about the centre of the side of the larger boiler; the small boiler must be quite full of water, and the larger one only about two-thirds full. The fire is then to be lighted beneath the larger boiler, to make the water boil, by which means the steam being confined, will be greatly compressed, and will, therefore, on opening a way for it to issue out (which is done by pushing the handle of a regulator from the operator), rush with great violence through a steam-pipe into a receiver, driving out all the air before it, sending it up into a force-pipe through a clack, as may be perceived from its noise; when the air is expelled, the receiver will be very much heated by the steam. When it is thoroughly emptied of atmospheric air, and grown very hot, which may be both seen and felt, then the handle of the regulator is to be drawn towards the operator, by which means the first steam-pipe will be stopped, so that no more steam can rise into the first receiver, by which means a second receiver will be filled in like manner. Whilst this is doing, some cold water must be poured on the first receiver, by which means the steam in it will be cooled, and thereby condensed into smaller room: consequently the pressure in the valve, or cock, at the bottom of the receiver—there being nothing to counterbalance the atmospheric pressure at the surface of the receiver in the inner part of the sucking-pipe, it will be pressed up into the receiver, driving up before it the valve at the bottom, which afterwards falling again, prevents the descent of the water that way. Then the first receiver being, at the same time, emptied of its air, push the handle of the regulator, and the steam which rises from the boiler will act upon the surface of the water contained in the first receiver, where the force or pressure on it still increasing its elasticity, till it exceeds the weight of a column of water in another receiving-pipe, then it will necessarily drive up through the passage into the force-pipe, and eventually discharge itself at the top of the machinery.
After the same manner, though alternately, is the first receiver filled and emptied of water, and by this means a regular stream kept continually running out of the top of a force-pipe, and so the water is raised very often from the bottom of a mine, to the place where it is meant to be discharged.