278 Lifting Pumps. [Book III. If the head of a common pump (No. 90) be closed, except an opening through which the rod works, or may be worked, it is then converted into a lifting pump, and will raise water to any elevation through a pipe attached to the spout. The earliest specimen that we have met with is represented by the 128th figure, from Agricola. Although a rude device, it is interesting as illustrative of the resources of old mining engineers, in modifying and applying the common wooden pump under a variety of circumstances. The upper parts of two atmospheric pumps terminate in a close chamber or strong box, (two sides of which are removed in the figure to show its interior,) their lower ends extending into water collected at a lower depth in the mine. From the top of the box a forcing pipe is continued to the surface of the ground, or to another level in the mine, from which the water raised through it can be discharged. The piston rods are worked by a double crank, one end of which turns in a socket formed in the inside of the chamber, and the other is continued through the opposite side and bent into a handle by which the laborer works the machine. Two collars are formed on the crank axle, one close to the outside, and the other to the inside of that part of the chamber through which it passes, and some kind of packing seems to have been used to prevent the water from leaking through. Four iron arms with heavy balls at their ends are secured to the axle to equalize the movement. These were the old substitutes for the modern fly-wheel: they were quite common in all kinds of revolving machinery in the 15th and 16th centuries. The modern form of the lifting pump is represented in figure No. 129. The working cylinder being generally brass or copper, and having a strong flanch at each end: the upper one is covered by a plate with a stuffing box in the centre, through which the polished piston rod moves; and the under one by another to which the suction pipe is attached, and whose orifice is covered by a valve. To the forcing or discharging pipe Chap. 4.] Lifting Pump with two Pistons. 279 a cock is commonly soldered as in No. 118, to supply water when required at the pump. This is one of the most useful forms of the pump for household purposes: it may be placed in the kitchen, cellar or yard, and will not only draw water from a well, but will force it up to every floor of a dwelling, and still answer every object of the ordinary atmospheric pump; and if an air-vessel be connected to the pipe, as in No. 120, it will then become a domestic fire-engine; and when a sufficient length of hose pipe is kept at hand, water may, in case of fire, be conveyed in a few moments to any part of the building. Desaguliers, a century ago, recommended this application of it, and it is surprising that it has not become more general. The following extract from a pump-maker's circular, 120 years since, refers to it. "Pumps which may be worked by one man, for raising water out of any well, upwards of 120 feet deep, sufficient for the service of any private house or family, and so contrived that by turning a cock, may supply a cistern at the top of the house, or a bathing vessel in any room; and by screwing a leather pipe the water may be conveyed either up stairs, or in at a window, in case of any fire." Switzer's Hydrostatics, 352. Although the valve in the ascending pipe is not an essential part of these pumps, it is a valuable addition, since it removes the pressure of the liquid column above it from the stuffing box, when the pump is not in use. The inventor of these pumps (and of the stuffing box) is unknown. They are described by Desaguliers, Belidor, and other writers of the last century as then common, and they are figured in the 6th volume of machines and inventions approved by the French Academy, p. 19. Sometimes the cylinder itself has been made to answer the purpose of an air-vessel. With this view it is made longer than usual, and the discharging pipe is connected to the middle of its length, below which the piston works. The air is therefore compressed in the upper part of the cylinder, but as it is liable to escape at the joints and through the stuffing box, a separate vessel is far preferable. Mr. Martin, in the 2d vol. of his Philosophy, has figured and described a pump of this kind, which he says was the invention of Sir James Creed. In 1815, the London Society of Arts awarded a silver medal and fifteen guineas for a lifting pump with two pistons. The cylinder was made twice the usual length, and each end furnished with a stuffing box through which two separate rods worked. The suction pipe being attached, like the forcing one, to the side of the cylinder; the lower piston was inverted having its valve on the top as in No..126. The outer ends of the rods were connected to the centre of two small wheels or friction rollers which moved between two guide pieces, and thus prevented the rods from deviating from the centre of the cylinders; the upper wheel was connected by a short rod to the pump lever as in the common pumps, and the other one by a longer rod (bent at its lower part) to the same lever, but on the opposite side of the fulcrum; so that as one was raised the other was lowered; hence the two pistons alternately approached to and receded from each other, and consequently one of them was always forcing up water whenever the machine was at work. Transactions Soe. Arts, vol. xxxiii. 115. We believe these pumps have never been much used, nor do we think they possess any advantages over two separate ones; for they are to all intents and purposes double pumps. The cylinders are twice the length of single ones-they have two pistons, two rods, two stuffing boxes, and double the amount of friction of single ones. Two distinct pumps are more economical. After one of the above has been a little while in use, air will unavoidably insinuate itself through the lower stuffing box and diminish or 280 Description of a Pump from Besson. [Book III. destroy the vacuum upon which the efficiency of the machine depends. The same remarks apply to these that were made on atmospheric pumps with two pistons, at page 227, There is a pump with two pistons in Besson's Theatre des Instrumens, which shows that such devices were known in the 16th century. It consists of a square trunk four or five feet in length, and the bore five or six inches across, immersed perpendicularly in water at the bottom of a well; its lower end being open and the upper one closed, except at the centre, where an opening is left and covered by a valve. A square piston, with its valve opening upwards, is fitted to work in the trunk from below by a rod connected to its under side, as in No. 126. A lever passes through the lower part of the trunk, (through slits made for it in two opposite sides,) one end of which is secured to a piece of timber walled in the well, by a pin, on which it moves; and the other end extends to the opposite side of the trunk, where it is hooked to a chain that reaches from the pump brake at the top of the well. The lower end of the piston rod is connected by a bolt to that part of the lever that is within the trunk. This apparatus forms the lifting or forcing part of the machine. A common pump tree or bored log extends from the place to which the water is to be raised, to the top of the trunk, and the junction with the latter made perfectly tight: an upper box or piston with its rod is fitted to work in the tree like an ordinary wooden pump, while the valve on the trunk answers the purpose of a lower box. This rod is attached to the brake on one side of the fulcrum and the chain that is connected to the lever and lower rod to the opposite side, so that as one piston rises the other descends and a constant stream of water is discharged above. This is the oldest pump with two pistons that we know of, and it has one advantage over others, viz: in raising water without changing its direction. We at first intended to insert a figure of it, but the apparatus for working it is too complicated for popular illustration. Although motion is imparted to the piston as noticed above, it is not done directly, but No. 130. Trevethick's Pump. by means of such an enormous amount of complex and Sometimes pumps with solid and hollow pistons are combined as in No. 130, a contrivance of Mr. Trevethick. The cylinder of a forcing pump communicates with that of an atmospheric one; both piston rods are connected to a cross-bar and rise and fall together. When the pistons are raised the water above that in the long (or atmospheric) cylinder is discharged at the spout, and the space below them is filled by the atmosphere forcing up fresh portions through the suction pipe. When Chap. 5.] Rotary Pumps. 281 the pistons descend, the valve on the suction pipe closes, and the solid piston drives the water in its cylinder through the hollow one in the other. so that whether rising or falling the liquid continues to flow. As both cylinders are filled at the same time, the bore of the suction pipe should be proportionably enlarged. The plate bolted over the opening at the lower part of one cylinder is to give access, in large pumps, to the lower valve. In some pumps both a solid and a hollow piston are made to work in the same cylinder. Such were those that constituted the "single-chamber fire-engine" of Mr. Perkins. A plunger worked through a stuffing box as in No. 123, and its capacity was about half that of the cylinder; consequently on descending it displaced only that proportion of the contents of the latter. The apertures of discharge were at the upper part of the cylinder, and a single receiving one at the bottom. From the lower end of the plunger a short rod projected, to which a hollow piston or sucker was attached, fitted to work close to the cylinder, so that when the plunger was raised, this piston forced all the water above it through the discharging apertures. To convert one of these pumps into a fire-engine, the cylinder of the pump was surrounded by a shorter one of sheet copper, the lower end of which was left open, and its upper one secured air-tight to the flanch of the pump; the space left between the two forming a passage for the water expelled out of the inner one. A larger and close cylinder encompassed the last, and the space between them was the air chamber, to the lower part of which a hose pipe was attached by a coupling screw in the usual way. Such pumps are more compact than those with two cylinders, but they are more complex, less efficient, and more difficult to keep in order and to repair. The friction of the plunger and sucker is much greater than that of the piston of an ordinary double acting pump of the same dimensions; and the latter discharges double the quantity of water; for although double acting, the effect of these pumps is only equal to single acting ones. For the above reasons they have, we believe, become obsolete or nearly so. CHAPTER V. ROTARY or rotatory pumps: Uniformity in efforts made to improve machines-Prevailing custom to convert rectilinear and reciprocating movements into circular ones-Epigram of Antipater-Ancient opinion respecting circular motions-Advantages of rotary motions exemplified in various machines— Operations of spinning and weaving; historical anecdotes respecting them-Rotary pump from Sérviere-Interesting inventions of his-Classification of rotary pumps-Eve's steam-engine and pumpAnother class of rotary pumps-Rotary pump of the 16th century-Pump with sliding butment-Trotter's engine and pump-French rotary pump-Bramah and Dickenson's pump-Rotary pumps with pistons in the form of vanes-Centrifugal pump-Defects of rotary pumps-Reciprocating rotary pumps; A French one-An English one-Defects of these pumps. No one can study the past and present history of numerous machines and devices without perceiving a striking uniformity in the efforts made to improve them in distant times and countries; the same general defects and sources of defects seem always to have been detected, and similar methods hit upon to remedy or remove them: the same ideas, moreover, led inventors to modify and apply machines to other purposes than those for which they were originally designed, and also to increase their effect by changing the nature and direction of their motions. So uniform have been 282 Conversion of Rectilinear and Alternating Motions. [Book III. the speculations of ingenious men in these respects, that one might be almost led to suppose they had reasoned, like the lower animals from a common instinct; and that the adage of Solomon, "there is no new thing under the sun," was as applicable to the inventions of man, as the works of nature. It would indeed be no very hard task to show that the preacher was correct, to an extent not generally believed, when he penned the following interrogatory and reply-"Is there any thing whereof it may be said,-See, this is new ?-it hath been of old time which was before us." Did a modern savan invent some peculiar surgical instruments of great merit?—similar ones were subsequently discovered in the ruins of Pompeii. Have patents been issued in late years for economizing fuel in the heating of water, by making the liquid circulate through hollow grate bars?—the same device has been found applied to ancient Roman boilers. And the recent practice of urging fires with currents of steam (also patented) was quite common in the middle ages. (See remarks on the Eolipile in the next book.) Numbers of such examples might be adduced from almost every department of the useful arts. From the earliest times it has been an object to convert, whenever practicable, the rectilinear and reciprocating movements of machines into circular and continuous ones. Old machinists seem to have been led to this result by that tact or natural sagacity that is more or less common to all times and people: thus the dragging of heavy loads on the ground led to the adoption of wheels and rollers-hence our carts and carriages :-the rotary movements of the drill and the wimble superseded the alternating one of the punch and gouge, in making perforations:-the horizontal wheel of the potter rendered modeling of clay vessels by hand no longer necessary: the whetstone gave way to the revolving grindstone:-the turning lathe produced round forms infinitely more accurate, and expeditiously than the uncertain and irregular carving or cutting away with the knife. The quern, or original hand mill, was more efficacious than the alternate action of the primitive pestle and mortar for bruising grain; and the various forces by which corn mills have subsequently been worked, have always been applied through revolving mechanism. The short handles, on the moveable stone, by which females and slaves moved it round, became in time lengthened into levers, and being attached to the peripheries of larger stones, slaves were sometimes yoked to them, who ground the grain by walking round a circular path. Subsequently slaves were replaced by animals, and these, in certain locations, by inanimate agents-wind and water. The period is unknown when man first derived rotary motion from the straight currents of fluids, for there is no sufficient reason to believe that the water mill located near the residence of Mithridates was the first one ever used in grinding corn: that may have been the one first known to the Romans; but it is very probable that such machines as well as wind mills were in use in Egypt, Syria, China, and other parts of Asia, in times that extend far beyond the confines of authentic history. An epigram of Antipater, a contemporary of Cicero, implies that water mills were not then very common in Europe. "Cease your work, ye maids, ye who laboured in the mill: sleep now, and let the birds sing to the ruddy morning, for Ceres has commanded the water nymphs to perform your task; these, obedient to her call, throw themselves on the wheel, force round the axle-tree, and by these means the heavy mill." Rotary motions were favorite ones with ancient philosophers: they considered a circle as the most perfect of all figures, and erroneously concluded that a body in motion would naturally revolve in one. To the substitution of circular for straight motions, and of continuous for |