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which at times they could command, is also pretty conclusively ascertained. What schoolboy has not read of the mysterious Memnon, whose mystic utterance of sounds has even yet, in these utilitarian days, "a distinct and mysterious interest, for no myth of the most graceful mythology is so significant as its story." Yet the "seven mystic vowels, which are the very heart of mysteries to us," are said to have been produced by some of those pneumatic contrivances which Hero describes. "When the secrets of the waning faith," says an elegant writer, "were revealed by the votaries of a rival belief, the celestial harmony was then said to be produced by vapour, rising from water concealed in a cavity of the statue, being made to pass through a tube having a small orifice fashioned in a manner similar to that of an organ. As long as the fluid was heated by the rays of the sun, mysterious sounds were heard by the assembled worshippers, which died gradually away as the solar influence was withdrawn from the gigantic idol."

At this stage of our progress an inquiry will naturally arise—how is it, that with all the ingenuity of the ancients, so fertile and so suggestive a power should have been allowed to remain developed only in the devices of priestcraft, and not adapted to the purposes of a more varied and general utility? The cause of this apparent neglect may be traced to the same sources which influenced the obscurity which has hid from later times the arts of antiquity. Another cause may be in the following, so well put by an able writer: "The ancient philosophers esteemed it an essential part of learning, to be able to conceal their knowledge from the uninitiated. And a consequence of their opinion that its dignity was lessened by its being shared with common minds, was their considering the introduction of mechanical subjects into the regions of philosophy a degradation of its noble profession; insomuch that those very authors among them who were most eminent for their invention, and were willing by their own practice to manifest unto the world their artificial wonders, were notwithstanding so infected by this blind superstition, as not to leave any thing in writing concerning the grounds and manner of these operations; by which means it is that posterity hath unhappily lost, not only the benefit of those particular discoveries, but also the proficiency of those arts in general. For when once learned men did forbid the reducing of them to vulgar use and vulgar experiment, others did thereupon refuse these studies, as being but empty and idle speculations; and the divine Plato would rather choose to deprive mankind of these useful and excellent inventions, than expose the profession to the vulgar ignorant." For centuries no attention seems to have been paid to the development of the power of steam; at least, history is a blank as to any notices thereof. Nevertheless, there are sufficient indications of the fact that its power was not altogether unobserved by philosophers and men attached to science; many in their writings hinting at the power to be derived from "vapour," and alluding confidently as to the capability of huge "engines" being forced into motion by the power of this agent. About the year 1121, according to William of Malmesbury," there were extant in a church at Rheims, as proofs of the knowledge of Gerbert, a public professor in the schools, a clock constructed on mechanical principles, and a hydraulic organ in which the air, escaping in a wonderful manner by the force of heated water, fills the cavity of the instrument, and the brazen pipes emit modulated tones through multifarious apertures."

On the revival of learning throughout Europe, the dissemination of the writings of the ancient philosophers doubtless attracted attention to many of these contrivances. There is some probability attached to the supposition that the invention of Blasco de Garay, a sea-captain, introduced into notice in 1543, was founded upon or derived from one of these. His invention was designed for the propulsion of vessels, and appears to have been very efficient. Unfortunately no record is known to exist from which a knowledge of its parts can be ascertained. The following is the only account extant: "Commissioners were appointed by the Emperor Charles the Fifth to test the invention at Barcelona, on the 17th June, 1543; and the result was, that a ship of 200 tons burden was propelled by the machine at a rate of three miles an hour." The moving force was obtained from a boiler containing water,-liable, as was said, to explosion; and paddle-wheels were the propelling power. Strange as it may appear, no further result was obtained from this trial, and the invention was lost sight of. Towards the close of the sixteenth century numerous expedients and mechanical contrivances for raising water were described in published works; these being based in principle on the contrivances detailed by Hero. Baptista Porta, in 1606, the well-known inventor of the camera-obscura, published a commentary on Hero's Pneumatica, in which he describes the

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arrangement which is illustrated in fig. 4. Let a be a furnace, and b a small boiler or receptacle for the water to be heated; on the steam rising up the tube c, which is continued nearly up to the top of the air-tight box dd containing water, it presses on the surface of the water and forces it out through the tube e, which is continued down nearly to the bottom of the box dd. This contrivance, although the author made no application of it for the purpose of raising water, is worthy of notice, if only for containing within itself the first known germ of an important distinction in steam-mechanism, namely, the adaptation of a separate vessel for containing the water to be raised, from that in which the steam or vapour was generated. Baptista Porta gives this arrangement merely as carried out in an experiment on the relative bulks of water and steam.

Solomon de Caus, in a work dated Heidelberg, in 1615, entitled, Les Raisons des Forces mouvantes avec diverses Machines tant utiles que plaisantes, amongst a variety of insignificant and fanciful theories and descriptions, gives an arrangement by which water is raised above its level.

In fig. 5 we give an illustration of De Caus' theorem on this point. Let a a be a ball of copper, having a pipe c by which to partially fill a a with water; another pipe bb reaching nearly to the bottom of the globe is also provided. On placing the globe on a fire and carefully stopping up the vent c, the steam or vapour pressing on the water in aa presses it up the tube bb. He also details the following illustration of the force of steam. "Take a ball of copper of one or two feet diameter and one inch thick, which being filled with water by a small hole, subsequently stopped by a peg so that neither air nor water can escape, it is certain that if the said ball be put over a great fire so that it may become very hot, it will cause so violent a compression that the ball will be shattered in pieces. It, however, required no experiment of this stamp to prove the force of steam; the ancients were by no means ignorant of this; indeed they went so far as to attribute earthquakes to the force of pentup vapours derived from subterranean heat. And Alberti, in 1412, notices the effects of pent-up vapour -dreaded by the lime-burners of that period-on the stones: "for when they come to be touched by the fire, and the stone grows hot, it turns to vapour, and bursting the prison in which it is confined with a tremendous noise, blows up the whole kiln with a force altogether irresistible."

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fig. 5.

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M. Arago, in his anxiety, we presume, to claim the merit of the discovery of the invention of the steam-engine to a countryman of his own, attributes to De Caus a higher and more philosophical knowledge of the capabilities of steam than one would suppose he was in possession of, merely from his recital of the above experiment; and states that the ideas of the ancients respecting the force of steam had never reached any thing like the numerical appreciation realised by such experiments as those of De Caus. On this point we cannot do better than quote from the able treatise on the steam engine edited by John Bourne, Esq., C.E.: "We confess that we are at a loss to understand wherein this numerical appreciation can consist; for although De Caus or Rivault may have ascertained that steam will burst a cannon-ball or bomb, they never ascertained what sort of ball or bomb steam will not burst; so that they did not establish any limit to the power of steam, but only showed that it is capable of very powerful effects."

In 1629, in a work published by Giovanni Branca, a description is given of a contrivance in which the force of steam was used as the actuating power. The water is heated in a vessel the upper part of which is fashioned like a head; from the lips of this a pipe or tube issues, which directs the steam against the vanes or boards of a wheel, made somewhat like an undershot wheel; this is made, by the impinging of the steam on the floats or vanes, to rotate rapidly. The wheel is placed horizontally, as b, fig. 6; in the vertical axis of this a small trundle c is placed, which actuates the face-wheel d, and gives motion ultimately to stampers for compounding drugs in mortars. It is believed by some writers that this machine was actually in use for the above purpose; by others, however, this

idea is discarded. And it is doubtful whether Branca was the real inventor, as his book is avowedly "a collection of machines invented by others; and

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fig. 6.

this mode of moving a wheel by steam is probably, therefore, an idea of which he is the mere illustrator." He was, however, a well as a person of ingenuity."

66 man of taste, as

From the period now arrived at, up to the middle of the seventeenth century, history has no record as to the advances of the improvement of the steam-engine. All the contrivances hitherto published seem to have been more the result of closet study than every-day practice; more to be looked upon as the playthings of our philosophers than the purposed inventions of the practical mechanic. To this, however, De Garay's steam-boat propeller may perhaps be an exception; nevertheless it can be classed only as an experiment-questionless a successful one-and the barren results of which, in all probability, arose from some inherent defect in its principle or construction. At all events, up to the interesting period we now approach, no useful application of steam to the practical purposes of everyday life had yet been successfully introduced.

In 1663 the Marquis of Worcester, a nobleman who had undergone many changes of fortune in the civil wars of England, published a work entitled "A Century of the Names and Scantlings of such Inventions as at present I can call to mind to have tried and perfected, which, my former notes being lost, I have, at the instance of a powerful friend, endeavoured now, in the year 1655, to set down in such a way as may sufficiently instruct me to put any of them in practice." Amongst the numerous devices which he enumerates, the following is the one which is closely connected with our present subject: "An admirable and most forcible way to drive up water by fire; not drawing or sucking it upward, for that must be, as one philosopher calls it, infra sphærum activitatis, which is not at such a distance: but this way hath no bounds if the vessel be strong enough; for I have taken a piece of a whole cannon whereof the end was burst, and filled it three-quarters full, stopping and screwing up the open 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 one to fill after the other, I have seen the water run like a constant fountain-stream forty feet high. One vessel of water rarefied by fire driveth up forty of cold water; and a man that tends the work has but to turn two cocks, that one vessel of water being consumed, another begins to force and refill with cold water, and so successively; the fire being tended and kept constant, which the selfsame person may likewise abundantly perform in the interim between the necessity of turning the said cocks." The connection between this, the sixty-eighth proposition of the Marquis, and the two following, being the ninety-eighth and one hundredth, has been pretty conclusively established by a writer in the second volume of the Glasgow Mechanic's Magazine: "An engine so contrived," says the proposition, "that working the primum mobile forward or backward, upward or downward, circularly or cornerwise, to and fro, straight upward or downright, yet the pretended operation continueth and advanceth, none of the motions above mentioned hindering, much less stopping, the other; but unanimously and with harmony agreeing, they all augment and contribute strength unto the intended work and operation; and therefore do I call this a semi-omnipotent engine, and do intend that a model thereof be buried with me." The next proposition is as follows: "How to make one pound weight to raise an hundred as high as one pound falleth, and yet the hundred pounds descending doth what nothing less than one hundred pounds can effect."

"Upon so potent a help as these two last-mentioned inventions, a waterwork is, by many years' experience and labour, so advantageously by me contrived, that a child's force bringeth up a hundred feet high an incredible quantity of water, even two feet diameter, so naturally, that the work will not be heard into the next room; and with so great care and geometrical symmetry, though it work day and night from one end of the year to the other, it will not require forty shillings' reparation to the whole engine, nor hinder one day's work; and I may call it the most stupendous work in the whole world and not only with little charge to drain all sorts of mines, and furnish cities with water, though never so high-seated, as well as to keep them sweet, running through several streets, and so performing the work of scavengers, as well as furnishing the inhabitants with sufficient water for their private occasions, but likewise supplying rivers with sufficient to maintain and make them portable from town to town, and for the bettering of lands all the way it runs. With many more advantages, and yet greater effects of profit, admiration, and consequence; so that deservedly I deem this invention to crown my labours, to reward my expenses, and make my thoughts acquiesce in the way of further inventions." "The primum mobile," says a writer of authority on the steam-engine, "is here evidently the force of steam, that, flow in whatever direction it may, is still capable of exerting the same mechanical power; and the movements, however numerous, can be made not to interfere with each other. The fall of a pound weight raising a hundred pounds weight clearly refers to a mechanism like a piston: one weighing a pound attached to a lever would raise one hundred pounds as high as one pound falleth; and were the weight of water to fall on a water-wheel, for instance, as is now often practised, it would raise a quantity very nearly equal to its own weight, and to the same height from which it fell. A child's force, too, would be sufficient to turn a cock even of a large engine; and the small noise made by this description of machinery, and its working day and night without intermission or im

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