Chap. 7.]

Water Lute-Safety Valves.

451

most pleasing and honorable circumstances connected with the history of Papin's labors, is the candid admission of several English writers of his great merits, and their generously expressing regret that his attention should have been diverted when he was so near realizing the most splendid reward. His name is however inseparably connected with the steamengine, and as long as the safety-valve shall be used the world will be his debtor.

It should not however be supposed that safety-valves were wholly unknown before Papin's time; on the contrary, they were frequently used, although this fact has not been noticed by any writer on the steamengine. The liability of stills and retorts to be rent asunder led old chemists to apply plugs to openings in those vessels, that the vapor might raise or drive them out and escape ere its tension exceeded the strength of the vessels: such were the plugs in ancient steam deities, see page 399. In some old works on distilling, conical plugs or valves are shown as fitted into cavities on the tops of boilers, and in some cases they were loaded. In the "Maison Rustique de Maistres Charles Estienne et Jean Liebault, Docteurs en Medecine," Paris, 1574, folio 196, 197, are figures of two close boilers in which the distilling vessels were heated: one formed a water, the other a vapor bath. On the top of each is a conical valve opening upwards. These served both to let out the superfluous steam and to introduce water. Glauber, who contributed several valuable additions to the mechanical department of chemistry, has figured and described, in his Treatise on Philosophical Furnaces, the modes by which he prevented glass retorts or stills from being burst by the vapor. A long stopple or conical valve was fitted to the neck of each, being ground air-tight to its seat, and loaded with a "cap of lead," so that when the steam became too "high" it slightly raised the valve and a portion escaped; the valve then closed again of itself, "being pressed down with the leaden cap and so stopt close." (English Translation, Lond. 1651, p. 306.) The valve on Newcomen's first engine was of this description. In the same work Glauber describes the most philosophical of all safety-valves, viz. a column of mercury enclosed in a bent tube which communicates with the boiler or still, somewhat like the modern mercurial gauge. He also describes that beautiful modification of it known among chemists as the water lute, or quicksilver lute: that is, around the mouth or neck of a vessel a deep cavity is formed and partly filled with water or mercury, as the case may be. A cylindrical vessel, open at top and closed at bottom, forms the cover: it is inverted, the open end being placed in the cavity and dipping as far into the liquid as the internal pressure may require. In "The Art of Distillation, or a Treatise of the choisest Spagyrical Experiments," &c. by John French, Doctor of Physic, Lond. 1651, the author describes the same devices for preventing the explosion of vessels as those mentioned by Glauber. Speaking of the action of such safety-valves he observes, (page 7) "upon the top of a stopple [valve] there may be fastened some lead, that if the spirit be too strong, it will only heave up the stopple and let it fall down again." Papin's claim therefore is not to the valve itself, but to its improvement, or rather to the mode of applying it by means of a lever and moveable weight; thereby not only preventing the valve from being blown entirely out of its place, but regulating the pressure at will, and rendering the device of universal application.

It was not till some years after Savery had introduced his steam machine that Papin proposed the following one, which he announced in a work entitled "Nouvelle maniére pour lever l'eau par la force du feu, mise en lumiére, par M D. Papin, Docteur en Med. Prof. en Mathém. a Casel,

452

Steam Machine by Papin.

[Book IV. 1707." It is inserted here out of chronological order, to keep this notice of his labors unbroken.

A copper boiler, A, is set in brick work and furnished with a safetyvalve, B, whose lever is loaded with the weight C. The steam pipe and cock D connect the boiler with the receiving cylinder F. A hollow float or piston is made to move easily in F, to prevent the steam from coming in contact with the water. A cavity is made in this float for the reception of an iron heater, Z, designed to keep up the temperature of the steam when the latter is admitted into F. The heater is admitted through the opening on the top of F, which is closed by the valve G. X, a funnel through which the water to be raised is introduced, which is kept from returning by closing the cock or valve H. The lower part of F is connected with the rising main K by a curved and tapered tube. The pipe K terminates in a reservoir or air chamber, whence the water is discharged by the pipe O upon an overshot wheel, cr conveyed to the place where it may be required. If the receiver be charged from below, a suction pipe (imperfectly represented by the pipe I) was continued to it from the under side of the curved pipe. The steam flowing through the pipe D presses down the piston, and the water beneath it is forced up the pipe K, (the valve at the lower part of K preventing its return.) When the piston has reached the bottom of F, the cock D is shut and the one marked E is opened. H is then opened, and the water rushes in and drives up the piston as before, when the operation is repeated. Water was raised by one of these machines to an elevation of 70 feet, whence it descended and formed a jet d'eau in the court of the Hessian Academy of Arts.

Belidor inserted a figure and description of this machine in the second volume of his Architecture Hydraulique, p. 328.

Chap. 8.]

Thomas Savery.

453

CHAPTER VIII.

Experimenters contemporary with Papin-Savery-This engineer publishes his inventions-His project for propelling vessels-Ridicules the Surveyor of the Navy for opposing it-His first experiments on steam made in a tavern-Account of them by Desaguliers and Switzer-Savery's first engine-Its operation-Engine with a single receiver-Savery's improved engine described-Gauge cocks-Excellent features of his improved engine-Its various parts connected by coupling screws-Had no safetyvalve-Rejected by miners on account of the danger from the boilers exploding-Solder melted by steam-Opinions respecting the origin of Savery's engine-It bears no relation to the piston engine -Modifications of Savery's engine by Desaguliers, Leopold, Blakey and others-Rivatz-Engines by Gensanne-De Moura-De Rigny-Francois and others-Amonton's fire mill-Newcomen and CawleyTheir engine superior to Savery's-Newcomen acquainted with the previous experiments of PapinCircumstances favorable to the introduction of Newcomen's engine-Description of it-Condensation by injection discovered by chance-Chains and Sectors-Savery's claim to a share in Newcomen's patent an unjust one-Merits of Newcomen and Cawley.

Both philosophers and mechanics were engaged in experiments on air and steam machines about the same time as Papin. Of these, Savery, Amontons, Newcomen and Cawley were the most successful. The two last named have not generally been considered so early in the field; but, from an observation of Switzer, such appears to have been the case. As weekly and monthly Journals of Arts' and' Mechanics' Magazines' had not then been introduced, those who were disposed to communicate their discoveries to the public had no appropriate medium for doing so, except by a separate publication, and this mode but an exceedingly small number of inventors ever adopted: hence it is that not only the dates of several modern inventions are uncertain, but numerous devices and valuable floating thoughts have, with their authors, been constantly passing into utter oblivion. The history of steam as a mechanical agent affords signal proofs of the advantages of inventors recording their ideas: thus the name of Decaus had long been forgotten, when an old tract of his was discovered containing the device we have figured at page 410. This he probably considered the most trifling thing in his book, yet on account of it a place has been claimed for him among the immortal authors of the steamengine. Moreland, of whose speaking trumpet an account was inserted in the sixth volume of the Philosophical Transactions, and his ideas of the power required to force water to different elevations in the ninth, omitted to publish through the same or any other medium a description of his steam-engine; and by this neglect has lost a large portion of honor that might have been attached to his name. The same may be said of Garay, Ramseye and Worcester. Savery, however, knew better, for he laid his machine before the Royal Society and got it noticed in their Transactions; and when he had subsequently improved it, he published a separate account with illustrations; in consequence of which he has sometimes been considered the author as well as describer of the first working steamengine.

Of Savery's personal history, less has transpired than of either Moreland's or Worcester's. He evidently was a man of great energy, who raised himself from obscurity by his talents-a self-made man. According to a tradition he commenced life as a working miner, and in process of time

454

Savery's Project for propelling Boats.

[Book IV.

He

became an engineer and thus acquired the title of Captain, agreeably to a custom which is said still to prevail among the Cornish miners. seems to have acquired a competence, if not wealth, previous to the commencement of his experiments on steam, and we shall find that he was as independent in his spirit as in his purse. Switzer, who was intimately acquainted with him, says he was a member of the board of commissioners for the sick and wounded; but this was probably in the latter part of his life, and subsequent to the introduction of his steam machines.

The first invention of Savery that we meet with is in a pamphlet published by him in 1698, on the propulsion of ships in a calm. His plan consisted of paddle-wheels to be worked by the crew. In the first edition of Harris's Lexicon Technicum, A. D. 1704, there is a description, and in the second, 1710, a figure of Savery's "engine for rowing ships." A horizontal shaft passes through the vessel between decks, and to each end a paddle-wheel is attached. On the middle of the shaft is a pinion or trundle wheel, and underneath a capstan upon which a cog wheel is fixed, whose teeth are made to work between those of the pinion. A number of bars are arranged in the capstan, and the crew were to apply their strength to these as in raising an anchor. As the officers of the admiralty after examination declined to adopt it, Savery tells them he had two other important inventions, which he would not disclose until they did him justice in this! He even held up his opponents to ridicule. On the Surveyor of the Navy, who reported against the adoption of his plan as one neither new nor useful, he was very severe. At that time large wigs were commonly worn, and Savery gave a smart rap on that which covered the head of his official adversary. "It is [he observed] as common for lies and nonsense to be disguised by a jingle of words, as for a blockhead to be hid by abundance of peruke." Had Savery been of a timid disposition, we should probably never have heard of him. After enduring one or two rebuffs in attempting to introduce his inventions, he would have retired and sunk unknown into the grave, like thousands of inventors before him.

Of the few incidents preserved respecting his private life, there are two from which it seems that he loved a glass of good wine and a pipe of tobacco; and that, to obtain them, he was in the habit of visiting a tavern. Let not those who eschew such things complain of us for unnecessarily mentioning them, for Savery's first experiments on steam were made in a bar-room, with a wine flask and a tobacco pipe! At such a place and with such implements he is said to have become acquainted with the principles of his famous machine. The circumstance has not been commonly known, or some scientific Boniface would, long ere now, have adopted Savery's head for a sign; and artists would have made him, in the act of experimenting, the subject of a picture. There is a rich but neglected field for historical painters in the facts and incidents connected with the origin and development of useful mechanism.

66

According to Desaguliers, Savery declared that he found out the power of steam by chance, and in the following manner: Having drank a flask of Florence [wine] at a tavern, and thrown the empty flask upon the fire, he call'd for a bason of water to wash his hands, and perceiving that the little wine left in the flask had filled up the flask with steam, he took the flask by the neck and plunged the mouth of it under the surface of the water in the bason; and the water of the bason was immediately driven up into the flask by the pressure of the air." This illustration of the ascent

66

455

of water into a vessel from which the air had been expelled by steam, was of course not new in Savery's time, although it appears to have been so to him. Switzer gives a different account. The first hint from which it is said he took this engine was from a tobacco pipe, which he immers'd to wash or cool it, as is sometimes done: he discover'd by the rarefaction of the air in the tube, by the heat or steam of the water and the gravitation or impulse of the exterior air, that the water was made to spring through the tube of the pipe in a wonderful surprising manner."a It was an old practice of veteran smokers, when their (clay) pipes became blackened through use, and more particularly when choked or furred up, to place them in a bright fire till they became red hot, then to remove and allow them to cool. By this operation they were whitened and purified like the incombustible cloth of the ancients, which was cleansed in the same way. But frequently when taken from the fire the mouths of the pipes were plunged slowly into water; steam was thus formed, and rushing through the tubes, was sometimes preceded, often accompanied, and sometimes followed by jets of water. There are however different causes, and far from obvious ones, for the liquid issuing through tobacco pipes under such circumstances, so that it is difficult to perceive what inference Savery drew from the experiment.

G

a

But whatever may have led Savery to the subject of steam, he had so far matured his ideas respecting its application to raise water as to erect several engines, and to secure patent as early as 1698. In June of the following year he submitted a working model to the Royal Society, and made successful experiments with it at the same time. A figure of this engine was published in the Transactions of that year, and may also be found in the first volume of Lowthorp's Abridgment. No. 193 is a copy. It consisted of a close boiler, B, set in a brick furnace A, and two receivers D D supported on a stand, and made of strong copper and air-tight. A suction pipe whose lower end descends into a well, or other place whence water is to be raised, (which may be about 24 feet below D D) and whose upper part, divided into two branches, communicates with the top of the receivers. Each branch is furnished with a valve at E E, opening upwards, to prevent the water from returning when once raised. lower part of the forcing pipe G has also two branches, FF, which communicate with the bottom of the receivers, and these branches have also valves, E E, like the others opening upwards. Each receiver has a communication with the upper part of the boiler by steam pipes and cocks C C.

No. 193. Savery's First Engine. A. D. 1698.

The

The operation was as follows:-The boiler was two thirds filled with

a Hydrostatics, edition of 1729, page 325.