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.

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 among 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.

"" 66

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."b 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 specifie 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.

66

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. An 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.

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. a Wilkins' Mat. Magic.

Chap. 4.]

Double acting Pump.

271

CHAPTER IV.

FORCING pumps continued: La Hire's double acting pump-Plunger pump: Invented by Moreland; the most valuable of modern improvements on the pump-Application of it to other purposes than raising water-Frictionless plunger pump-Quicksilver pumps-Application of the principle of Bramah's press by bees in forcing honey into their cells. Forcing pumps with hollow pistons: Employed in French water-works-Specimen from the works at Notre Dame-Lifting pump from Agricola-Modern lifting pumps-Extract from an old pump-maker's circular-Lifting pumps with two pistons--Combination of hollow and solid pistons-Trevethick's pump-Perkins' pump.

Or the various modifications which the forcing pump has undergone in recent times we can notice but a few, and of these the greater part were most likely known to ancient engineers. The most prominent one is that by which the machine is made double acting. Now the device by which this is effected has not only frequently occurred to quite a number of ingenious men in their endeavours to improve the pump who were ignorant of its having been accomplished; but it is an exact copy of one that has been applied to the wind pump of China from time immemorial, (see No. 112;) it probably therefore did not escape such men as Ctesibius, and Heron, and others who appear to have exercised their ingenuity and sagacity to the utmost in order to improve this machine, and who were enthusiastically attached to such researches. The remarks on modern improvements of the atmospheric pump, pages 225-6, are equally applicable to those of the forcing one; and it is worthy of remark, that notwithstanding the present improved state of mechanical science, the ancient forms of both now prevail-for the forcing pump as made by Ctesibius in Egypt, and as described by Vitruvius as used by the Romans, is still more common than any other.

A

I

The double acting pump represented in the figure, was devised by M. La Hire in the early part of the last century. His description of it was published in the Memoirs of the French Academy in 1716; and from one of his expressions we perceive (what was indeed very natural) that if he was not indebted for the improvement to the contemplation of bellows, these instruments were at least closely associated with it in his mind. The pump propose [he observes] furnishes water continually, "just as the double bellows makes a continual wind." The piston rod passes through a stuffing box or collar of leathers on the top of the cylinder. The latter has four openings covered by valves or clacks; two for the admission of water and the same number for its discharge. A B is the suction pipe, B and C D the ascending or discharging one. Suppose the lower end of the suction pipe in water; then if the piston be thrust down, the valve near B will close, and the air in the lower part of the cylinder will be forced through the valve at D and up the pipe D C, and in consequence of the rarefaction of the air above the piston, the valve at C will be

272

Plunger Pump,

[Book III. closed, and water will ascend through B A and enter the cylinder at A; then if the piston be raised it will force all the water above it through the valve at C, the only passage for it, while at the same time a fresh portion will enter the cylinder through the valve at B. Thus at every stroke of the piston, whether up or down, the contents of the cylinder are forced out at one end, and it is replenished at the same time through the other; this pump therefore discharges double the quantity of water that an ordinary one of the same dimensions does. The piston rod may be inserted through either end of the cylinder, as circumstances may require. These pumps are frequently used in a horizontal position.

Another variation of the forcing pump consists in making the piston of the same length as the cylinder but rather less in diameter, so that it may be moved freely in the former without touching the sides. These pistons are made wholly of metal and turned smooth and cylindrical, so as to work through a stuffing box or cupped leathers. The quantity of water raised at each stroke has therefore no reference to the capacity of the cylinder, however large that part of one of these pumps may be, for the liquid displaced by the piston can only be equal to that part of the latter that enters the cylinder. Switzer has given a figure and description of an old engine composed of three of these pumps "that has been some years erected in the county of Surrey." Newton has figured the piston bellows described by Vitruvius as furnishing wind to hydraulic organs in a similar way. In Commandine's translation of Heron's Spiritalia, page 159, the same kind of plunger is figured in a pump belonging to a water organ; and at p. 71, a fire-engine, with two working cylinders, has pistons of the same kind. These pistons were formerly named plungers, and the pumps plunger-pumps. Their construction and action will be understood by the

figure, which represents one of a number that were employed in the water-works, York Buildings, London, in the last century. The piston was of brass, cast hollow and filled with lead, the outside being "turned true and smooth." A short rod attached to the upper end of the piston was connected by a chain to the arched end of a vibrating beam, that was moved by one of Newcomen's engines. The piston was therefore merely raised by the engine, while its own weight carried it down to render it sufficiently heavy for this purpose, a number of leaden disks (or cheeses, as they were named from their form) having holes in their centres, were slipped over the rod and rested upon the piston, as in the figure. These were increased until they were found sufficient to press down the piston and force the water up the ascending pipe. The cupped leathers through which the piston worked, were similar to those now used in the hydrostatic press. A small cistern was sometimes formed on the top of the pump, that the water it contained might prevent air from entering through the stuffing box or between the cupped leathers: it served also to charge the pump through a small pipe or cock. A valve opening upwards was sometimes placed just above the plug of the cock, and the latter left open when the machine was started, that the air within the cylinder might escape; and as soon as the water rose and filled the pump, the cock was shut. It is immaterial at what part of the cylinder the forcing or ascend