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Description of the Machine of Ctesibius by Vitruvius. [Book III.

ment; its flow from the discharging orifice being merely rendered uniform, or nearly so.

In the ordinary use of forcing pumps a constant instead of an interrupted flow of water from the discharging orifice, may be a matter of no importance; but when those of large dimensions are required to raise it to great elevations, air vessels are not only valuable but indispensable adjuncts; for the elastic fluid within them forms a medium for gradually overcoming the inertia of the ascending liquid columns, and thereby prevents those jars and shocks which are incident to all non-elastic substances in rapid motion, when brought suddenly to a state of rest. A column of water moving with great velocity through a pump, produces, when instantly stopt, a concussion like that of a solid rod of the same length, when its end is driven against an unyielding object; but with an air-vessel, the effect is like that of the same rod when brought in contact with a bale of cotton or caoutchouc. Less force is required also to work pumps that have air-vessels, because in them the column of water in the discharging pipe is continued in motion during the ascent of the piston, hence it has not to be moved from a state of rest on the piston's return. When two or more cylinders are connected to one discharging pipe, one air-vessel only is required, as in fire-engines, water-works, &c.

It is this kind of forcing pump that is generally adopted in water-works for the supply of towns and cities; the piston rods being moved by cranks or levers attached to water wheels: sometimes they are driven by windmills, steam-engines, and by animals. The cylinders are commonly used perpendicularly as in the figure, but they are sometimes worked in an inclined and also in a horizontal position.

The celebrated pump of Ctesibius was constructed like that represented in the last figure, except that it had two cylinders. It seems to have been almost identical in its construction with our fire-engines. "It remains now [says Vitruvius] to describe the machine of Ctesibius which raises water very high. This is made of brass; at the bottom a pair of buckets [cylinders] are placed at a little distance, having pipes like the shape of a fork annexed, meeting in a basin in the middle. At the upper holes of the pipes within the basin, are made valves, hinged with very exact joints; which, stopping the holes, prevent the efflux of the water that will be pressed into the basin by the air. Upon the basin a cover like an inverted funnel is fitted, which is adjoined and fastened to the basin by a collar, riveted through, that the pressure of the water may not force it off: and on the top of it, a pipe called the tuba, is affixed perpendicularly. The buckets [cylinders] have valves placed below the lower mouths of the pipes, and fixed over holes that are in their bottoms: then pistons turned very smooth and anointed with oil, being inclosed in the buckets [cylinders] are worked with bars and levers from above; the repeated motion of these, up and down, pressing the air that is therein contained with the water, the holes being shut by the valves, forces and extrudes the water through the mouths of the pipes into the basin; from whence rising to the cover, the air presses it upwards through the pipe; and thus from the low situation of the reservoir, raises it to supply the public fountains." Book x, cap. 12. Newton's Trans.

The machine as thus described is a proof of the progress which the ancients had made in hydraulics: the whole appears to have been of the most durable materials, and of the best workmanship. Although the figures of this and other machines which Vitruvius inserted in his work are lost, there is little difficulty in realizing its construction from the text. Transla

Chap. 3.]

Machine of Ctesibius.

267

tors and commentators have generally agreed in their views of it as represented below, viz: two ordinary forcing pumps connected to an airvessel and one discharging pipe.

The cylinders are secured in a frame of timber, and the piston rods are attached by joints to levers, one end of which are depressed by cams on the axis of the wheel, as shown above and also at No. 89. Barbaro has figured a crank at the axis which gives a reciprocating motion to a horizontal shaft placed over the pumps, and projecting pieces from which impart motion to the piston rods. Vitruvius informs us that when machines were employed to raise water from rivers, they were worked by undershot wheels impelled by the stream, and hence the pumps of Ctesibius were believed to have been moved by the same means.

But for Vitruvius we should not have known that forcing pumps constituted part of the water works of antiquity; and had he not remarked that they were employed to supply "public fountains," it might have been supposed that water never rose higher in the dwellings of ancient cities than that which was drawn directly from the aqueducts.

It would be almost unpardonable to pass over this celebrated machine without further remark, since it is, in several respects, one of the most interesting of all antiquity. An account of its origin and early history would form a commentary on most of the arts and sciences of the ancients, and would, we believe, furnish evidence of their progress in some of them that few are willing to believe. Although it was attributed to Ctesibius, there is some uncertainty respecting the extent of his claims. It may appear invidious to attempt to rob this illustrious man of inventions ascribed to him, but our object is to ascertain, not to depreciate them or diminish

268

Claims of Ctesibius,

[Book III. their number. It has frequently been remarked that little dependence can be placed on ancient writers as regards the authors of the useful machines. Generally those who introduced them from abroad, who improved them, increased their effects, or extended their application, were reputed their inventors. This has been the case more or less in every part of the world, and is so at the present day. The Greeks found authors among themselves for almost every machine, although most of them were certainly derived from Egypt. Thus, the sails and masts of ships, the wedge, auger, axe and level, were known before Dædalus. The saw, drill, compasses, glue and dovetailing, before Talus. Cast iron was employed, and moulding practiced, and the lathe invented, long before Theodorus of Samos lived; and the screw and the crane before Archytas. The last individual was celebrated for various inventions, and among others, Aristotle mentions the child's rattle, from which it may be inferred that he was an amiable man and fond of children-but Egyptian children were amused with various species of toys, centuries before he flourished; and they then had dolls whose limbs were moved by the pulling of strings or wires, as ours have at this day. Wilkinson's Manners and Customs of the Ancient Eygptians. Vol. ii, 426–7.

among

As regards machines for raising water, we have already seen, that some have been ascribed to others than their authors. Even the siphon has been attributed to Ctesibius, (Adams's Lectures, vol. iii, 372,) because it was found in the construction of his clepsydra, and no earlier application of it was then known; but it is now ascertained to have been in common use his countrymen in the remote age of Rameses-in the Augustan era of Egypt, when the arts, we are informed, "attained a degree of perfection, which no after age succeeded in imitating." Had the "Commentaries of Ctesibius" to which Vitruvius referred his readers for further information, been preserved, we should have had no occasion to attempt a definition of his claims to the forcing pump; unfortunately, however, these and Archimedes' Treatise on Pneumatic and Hydrostatic Engines have perished, and have left us in comparative ignorance of the history of such machines among the ancients.

We have already seen that the syringe was in common use ages before Ctesibius, and that it was employed by philosophers to illustrate their hypothesis of water rushing into a vacuum. Now a forcing pump is merely a syringe with an additional orifice for the liquid's discharge, and having both its receiving and discharging orifices covered by valves or clacks. Ctesibius therefore did not invent the piston and cylinder, nor was he the first to discover the application of these to force water, for they were in previous use and for that purpose. Was he the inventor of valves? No, for they were usedin the Egyptian bellows thirteen or fourteen hundred years before he lived, and appear always to have been an essential part of those instruments. They were employed in clepsydra; and were most likely used in the hydraulic organ of Archimedes, which Tertullian has described. Is the arrangement of the valves, by which water is admitted through one and expelled by the other, to be ascribed to him? We believe not, for the same arrangement was previously adopted in the bellows, so far as regards the application of one of them, and the principle of both : and if it could be shown that the Chinese bellows was then in use, as we suppose it was, and possibly known in Egypt, (for that some intercourse did take place in ancient times betwen Egypt and China, even if one people be not a colony of the other, is proved by Chinese bottles and inscriptions found in the tombs at Thebes,) then the merit of Ctesibius would seem to be confined principally to the construction of metallic bellows as

Chap. 3.]

To the invention of the Pump limited.

269

"water forcers," or, to the application of valves to the ordinary syringe, by which it was converted into a forcing pump, either for air or water. But it is not certain that the last was not done before, for neither Vitruvius nor Pliny asserts that "water forcers" were not in previous use. The former says he applied the principle of "compressed air" to them, in common with "hydraulic organs,' automatons," lever and turning machines," and " water dials," (Book ix, cap. 9;) hence it may as well be concluded from this passage, that he invented these as the pump. It is, indeed, almost impossible to believe that the Egyptians, of whose sagacity and ingenuity, unrivalled monuments have come down, did not detect the application both of the bellows and syringe to raise water long before Ctesibius lived; hence we are inclined to place the forcing pump in its simplest form, with the syringe and atmospheric pump, among the works

"Of names once famed, now dubious or forgot

And buried 'midst the wreck of things that were."

That the forcing pump was greatly improved by Ctesibius, there can be no question; but that which gave celebrity to his machine was probably the air-vessel, an addition, which though not very clearly described by Vitruvius, appears to have originated with him. By it the pump instead of acting as before like a squirt or syringe produced a continuous stream as in a jet d'eau, a result well adapted to excite admiration, and to give eclat to his name. The whole account of his machine shows its connection with and dependence upon air; whereas had it been simply a forcing pump it would have had nothing to do with it: it would have raised water independently of it; and without an air-vessel Vitruvius never could have asserted that it forced water up the discharging tube by means of "air pressing it upwards." Compressed air acted a prominent part in all his machines. In his wind guns, water clocks, and numerous automata; some of the latter in the shape of birds, &c. appeared to sing, others "sounded trumpets," and these results are said to have been produced with "fluids compressed by the force of air." We may add that he compressed air in his hydraulic organs and precisely in the same manner as in the pump, viz: by water, and by either air or water forcing pumps. The commencement of his discoveries was the experiment on air with the weight and speculum in his father's shop, (see page 122) in which the descending weight "compressed the inclosed air" and forced it through the several apertures into the open air, and thereby produced distinct sounds. " When therefore Ctesibius observed that sounds were produced from the compression and concussion of air, he first made use of that principle in contriving hydraulic organs, also water forcers, automatons," &c. What principle was this which Vitruvius says he applied to water forcers in common with organs, &c.? That of compressed air, as we understand it; and the employment of which is so evident, in the description of his machine already given.

Does any one doubt that the air-vessel was known to, and used by Ctesibius! Let him recollect that Heron, his disciple and intimate friend, has also described it; for the celebrated fountain of this philosopher, which still bears his name, and remains just as he left it, is simply an air-chamber, in which the fluid is compressed by a column of water instead of a pump; and one of his machines for raising water by steam, was another, in which the elasticity of that fluid was used in a similar manner. Besides these, there are others represented in the Spiritalia; indeed, a great portion of the figures in that work are modifications of air chambers. At pages 42 and 118, of Commandine's Translation, are shown

270

Air Chamber.

[Book III. spherical vessels containing water, into which perpendicular discharging tubes descend to expel the liquid, syringes or minute pumps are adapted to the vessels, for the purpose of injecting air or water, and by that means to produce jets d'eau. The common syringe is also figured at large and in section, p. 120. Pliny also seems to refer to air-vessels in his xix book, cap. 4, where he speaks of water forced up "by pumps and such like, going with the strength of wind enclosed." Holland's Trans.

As the ancients have not particularized the claims of Ctesibius to the pump, it is impossible to define them with precision at this distance of time. Perhaps the instrument had been laid aside, or the knowledge of it almost lost when he revived and improved it, as some of his own inventions have been in modern times-his gun, for example, of which Philo of Byzantium has given a description, and which " was constructed in such a manner as to carry stones with great rapidity to the greatest distance." Its invention has been claimed by the Germans, the French, Dutch, and from the following remark of Blainville, by the Swiss also: speaking of Basil, he observes, "They make a great noise here about a hellish invention of a gunsmith, who invented wind guns and pistols. This invention may be truly called diabolical, and the use of it ought to be forbid on pain of death." Now if the modern inventor of the air gun, an instrument which, two centuries ago, was spoken of as "a late invention,"d cannot with certainty be ascertained, it can hardly be expected that the specific claims of Ctesibius to the pump can be pointed out after a lapse of 2000 years. If he was the first to combine two or more cylinders to one discharging pipeto form them of metal, as well as the valves and pistons-and the first to invent and apply air-vessels, his claims are great indeed, and for aught that is known to the contrary he is entitled to them all. His merits as respects the latter will be apparent, if we call to mind the fact that their application to pumps has not been known in Europe for two centuries; and that their introduction was in all probability derived from him, for it was not till a hundred years after Vitruvius's description of his machine had been translated, printed and circulated, that we first hear of air-vessels in modern times.

We may here remark that at whatever period tobacco was first smoked in the Hookah, (and according to some authors, this weed was used in Asia before the discovery of America,) the air-vessel was known; for that instrument is a perfect one, as any person may prove by the following experiment: let a smoker, instead of sucking at the end of the tube which he inserts in his mouth, blow through it, and the liquid contents of the hookah will be forced out through the perpendicular tube on which the weed is placed as in a miniature fire-engine, carrying up with it the pellet of tobacco, somewhat in the manner of those light-balls which are sometimes placed on jets d'eau, or the boy's pea playing on a pipe stem. operation, in the opinion of some physicians, more beneficial to the performer than the ordinary one, and disposing of the scented material in a manner more suited to its value.

An

a Heronis Alexandrini Spiritalium liber. A Federico Commandino urbinate, ex Græco nuper in Latinum conversus. 1583.

Duten's Inquiry into the Origin of the Arts attributed to the Moderns, p. 186. Travels, i, 388. Wilkins' Mat. Magic.