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 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. 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.

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.

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.

Of 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, 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

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 pur pose, 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

Chap. 4.]

Invented by Moreland.

273

ing pipe is attached, whether at the bottom, near the top, or at any intermediate place. Small pumps of this kind are now commonly employed to feed steam boilers and for other purposes, and are worked by levers like the ordinary lifting and forcing pumps, the pistons being preserved in a perpendicular position by slings, &c.

These pumps are believed to be of English origin, having been invented by Sir Samuel Moreland, "master of mechanics" to Charles 2d. Like some old philosophers, he exercised his ingenuity in improving hydraulic and other engines, for raising water. Besides the plunger pump, for which he obtained a patent in 1675, he invented a "cyclo-elliptic movement" for transmitting motion to piston rods, a figure of which is inserted by Belidor in the second volume of his Arch. Hydraulique. He is also the reputed inventor of the speaking trumpet, of a capstan, and a steam-engine. In 1681 he made experiments with an engine consisting of two or more of his pumps at Windsor, in presence of the king and court, during which he forced water from the Thames in a continual stream to the top of the castle; and according to Dr. Hutton, " sixty feet higher." Moreland visited France the same or the following year, by order of the king, to examine the famous water-works at Marli, and while in Paris he exhibited models of his pump before the French court, and also constructed several for his friends. In 1683 he presented an account of various machines for raising water to Louis 14th, in a manuscript volume written and ornamented with much elegance; and in 1685, an account of his improvements was published in Paris in a work entitled, "Elévation des eaux par toute sorte de machines, réduite à la mesure, au poids, à la balance, par le moyen d'un nouveau piston et corps de pompe; et d'un nouveau mouvement cyclo-elliptique, et rejetant l'usage de toute sorte de manivelle ordinaires, par le Chevalier Moreland." It does not appear that he ever published this work in England, for Switzer had recourse to Ozanam, a French writer, for a description of Moreland's pump; as he could procure no English account of it, "having taken great pains to find out what Sir Samuel had left on that head to no purpose." Ozanam states that Moreland spent " twelve years study and a great deal of money" to bring this pump to perfection; and without this new invention it would have been impossible to have reduced the raising of water to weight and measure, as he has done." The latter observation refers to the leaden weights placed on the piston rod, and the quantity of water raised by them: the water and the elevation to which it was raised being compared with the sum of the weights employed to force it up.b

If we mistake not this is the most valuable and original modification of the forcing pump that modern times have produced. The friction of the piston is not only greatly reduced, but the boring of the cylinder is dispensed with; an operation of considerable expense and difficulty, particularly so, before efficient apparatus for that purpose was devised. Another advantage is the facility of tightening the packing without taking out the piston or even stopping the pump. The value of Moreland's invention in

There is an instrument very like a speaking trumpet in the hands of a figure in one of the illustrations of the Eneid, executed in the fourth or fifth century, in the 25th plate of "Painting" in D'Agincourt's History of the Fine Arts. It is a conical tube, the length being equal to that of the individual using it; and by which he appears to direct, from the top of a tower, the combatants below. Kircher has given a figure of a trumpet through which he supposed Alexander spoke to his army.

See Switzer's Hydrostatics, plate 25, pp. 302, 357. La Motraye's Travels, vol. iii, Lon. 1732. Desaguliers' Philos. vol. ii, 266. Belidor's Architecture Hydraulique, tom. ii, 61, and L'Art Ď'Exploiter Les Mines, in Arts et Metiers, page 1058, and planche 47.

the estimation of engineers appears from the increasing employment of it. It is, moreover, for aught that is known to the contrary, the parent of the common lifting pump; and to its inventor the double acting steamengine of Watt is in some measure due, the efficiency of that noble ma chine depending entirely upon closing the top of the cylinder and passing the piston rod through a stuffing box-both of which had already been done in this pump. Steam-engines have also been constructed on the same plan as these pumps; one long piston playing in two horizontal cylinders, and the power transmitted from it by means of a cross-head attached to the middle of its length, and on that part which moves between the stuffing boxes. Another celebrated machine is also copied from them --Bramah's hydrostatic press is one of Moreland's pumps.

There is another species of plunger pumps in which the stuffing box is dispensed with, and consequently the piston works without friction.

A

square wooden tube, or a common pump log of
sufficient length, and with a valve at its lower
end is fixed in the well as shown in the figure.
The depth of the water must be equal to the
distance from its surface to the place of delive-
ry; and a discharging pipe having a valve
opening upwards is united to the pump tree at
the surface of the water in the well. The pis-
ton (a solid piece of wood) is suspended by a
chain from a working beam, and loaded suffi-
ciently with weights to make it sink. As the
liquid enters the pump through the lower valve,
and stands at the same level within as without,
whenever the piston descends, it necessarily dis-
places the water, which has no other passage
to escape but through the discharging pipe, in
consequence of the lower valve closing. And
when the piston is again raised as in the figure,
a fresh portion of water enters the pump and is
driven up in like manner.

Dr. Robison observes that he has seen a machine consisting of two of these pumps, made by an untaught laboring man. The plungers were suspended from the ends of a long beam, on the upper surface of which the man walked, as on the picotah of India. He stood on one end till one plunger descended to the bottom of its tube, and he then walked to the other end, the declivity at first being about 250, but gradually growing less as he advanced. In this way he caused the other plunger to descend, and so on alternately.

No. 124. Frictionless Plunger
Pump.

By this machine a feeble old man whose weight was 110lbs. raised 7 cubic feet of water 11 feet high in a minute, and wrought eight or ten hours every day. A stout young man weighing 134lbs. raised 8 cubic feet to the same height in the same time. The application of this pump is extremely limited, and there is a waste of power in the water that is uselessly raised around the piston at every stroke.

The pistons of preceding machines are made of solid materials; but the pump now to be described has a liquid one. It was invented about the year 1720, by Mr. Joshua Haskins, who made the first experiment with it in the house and presence of the celebrated Desaguliers. His design