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 left between the two forming a passage pump; the space 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 pis tons 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

Chap. 5.]

Into Continuous Circular Ones.

283

alternating ones may be attributed nearly all the conveniences and elegancies of civilized life. It is not too much to assert that the present advanced state of science and the arts is due to revolving mechanism; we may speak of the wonders that steam and other motive agents have wrought, but what could they have done without this means of employing them? The application of rotary, in place of other movements, is conspicuous in modern machinery; from that which propels the stately steam ship through the water, and those flying chariots named "locomotives" over the land, to that which is employed in the manufacture of pins and pointing of needles. It is by this that the irregular motion of the ancient flail and primeval sieve, have become uniform in thrashing, bolting and winnowing machines; -hence our circular saws, shears and slitting mills;-the abolition of the old mode of spreading out metal into sheets with the hammer, by the more expeditious one of passing it through rollers or flatting mills and hence revolving oars or paddle wheels for the propulsion of vesselsthe process of inking type with rollers in place of hand balls-rotary and power printing presses-and revolving machines for planing iron and other metals instead of the ancient practice of chipping off superfluous portions with chisels, and the tedious operation of smoothing the surfaces with files.

But in few things is the effect of this change of motion more conspicuous than in the modern apparatus for preparing, spinning and weaving vegetable and other fibres, into fabrics for clothing. The simple application of rotary motions to these operations has in a great degree revolutionized the domestic economy of the world, and has increased the general comforts of our race a hundred fold. From the beginning of time females have spun thread with the distaff and spindle: Naamah the antediluvian, and Lachesis and Omphale the mythological spinsters, have been imitated in the use of these implements by the industrious of their sex in all ages and countries to quite modern days, and even at present they are employed by a great part of the human family. In India, China, Japan, and generally through all the East, as well as by the Indians of this hemisphere, this mode of making thread is continued: the filaments are drawn from the distaff and twisted by the finger and thumb, the thread being kept at a proper tension by a metallic or other spindle, suspended to it like the plummet of a builder's level, and the momentum of which, while turning round, keeps twisting the yarn or thread in the interim of repeating the operation with the fingers. The thread as it is

a There are numerous allusions in history to this primitive mode of spinning, that are highly illustrative of ancient manners. At the battle of Salamis, Queen Artemisia commanded a ship in the Persian fleet, and Xerxes, as a compliment to her bravery, sent her a complete suit of armor, while to his general (who was defeated) he presented a distaff and spindle. When Pheretine applied to Euelthon of Cyprus for an army to recover her former dignity and country, he intimated the inpropriety of her conduct by sending her a distaff of wool and a golden spindle. Herod. iv, 162. Hercules attempted to spin in the presence of Omphale, and she bantered him on his uncouth manner of holding the distaff. Among the Greeks and Romans, the rites of marriage directed the attention of women to spinning; a distaff and fleece were the emblems and objects of the housewife's labors; and so they were among the Jews-"A virtuous woman [says Solomon] layeth her hands to the spindle and her hands hold the distaff." When Lucretia was surprised by the visit of Collatinus and his companions of the camp, although the night was far advanced, they found her with her maids engaged in spinning. A painting found in Pompeii represents Ulysses seated at his own gate, and concealed under the garb of a beggar; Penelope, who is inquiring of the supposed mendicant for tidings of her husband, holds in one hand a spindle, as if just called from spinning. On the monuments of Beni Hassan both men and women are represented spinning and weaving. Several Egyptian spindles are preserved in the museums of Europe. See an account of a female in Sardis spinning while going for water, at page 22.

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[Book III. formed is wound round the spindle. In 1530 Jurgen of Brunswick devised a machine which dispensed with this intermitting action of the fingers, i. e. he invented the spinning wheel, which rendered the operation of twisting the filaments uniform. The wheel, however, like the primitive apparatus it was designed to supersede, produced only one thread at a time; but in the last century Hargreaves produced the "spinning jenny,' by which a single person on turning a wheel, could spin eighty-four threads at once; then followed the "rollers" of Arkwright, the "mule" of Crompton, to which may be added the "gin" of Whitney, and also "carding engines,' in place of the old hand cards, all composed of and put in motion by revolving machinery :-these have indefinitely extended the spinning of thread, and relieved females from a species of labor that, more than any other, occupied their attention from the beginning of the world; and lastly "power looms" impelled by water, wind, steam, or animals (through the agency of circular movements) are rapidly superseding the irregular and alternating motion of human hands in throwing the shuttle to and fro.

The conversion of intermitting into continuous circular movements is also obvious in ancient devices for raising water. The alternate action of the swape, the jantu and vibrating gutter thus became uninterrupted in the noria and tympanum-the irregular movement of the cord and bucket became uniform in the chain and pots; and so did the motion of the pitcher or pail as used by hand, when suspended to the rim of a Persian wheel. And when the construction of machines did not allow of a suitable change or form, they were often worked by cranks or other similar movements; (of this several examples are given in preceding pages;) but in no branch of the arts has this preference for circular movements over straight ones been so signally exhibited as in the numerous rotary pumps and steam engines that have been and still are brought forward; and in no department of machinery has less success attended the change. Most of these machines that have hitherto been made may be considered as failures; this result is consequent on the practical difficulties attending their construction, and the rendering of them durable. These difficulties (which will appear in the sequel) are to a certain extent unavoidable, so that the prospect of superseding cylindrical pumps and steam-engines is probably as remote as ever.

At an early stage in the progress of the machines last named, it became a desideratum with engineers to obtain a continuous rotary movement of the piston rod in place of the ordinary rectilinear and reciprocating one, that the huge "walking beam," crank and connecting shaft might be dispensed with, the massive fly-wheel either greatly reduced or abandoned, and the power saved that was consumed in overcoming their inertia and friction at every stroke of the piston. Reasoning analogous to this had long before led some old mechanicians to convert the motion of the common pump rod into a circular one; in other words, to invent rotary or rotatory pumps. By these the power expended in constantly bringing all the water in the cylinder and suction pipe, alternately to a state of rest and motion was saved, because the liquid is kept in constant motion in passing through them. The steam engine was not only originally dedesigned as a substitute for pumps to raise water, but in all the variety of its forms and modifications it has retained the same analogy to pumps as these have to bellows. One of the oldest of modern rotary steam engines, that of Murdoch, was a copy of an old pump, a figure of which, No. 131. is taken from Sérviere's collection.

Two cog wheels, the teeth of which are fitted to work accurately into each other, are enclosed in an elliptical case. The sides of these wheels

Chap. 5.]

Rotary Pump from Sérviere.

285

turn close to those of the case, so that water cannot enter between them. The axle of one of the wheels is continued through one side of the case, (which is removed in the figure to show the interior,) and the opening made tight by a stuffing box or collar of leather. A crank is applied to the

end to turn it, and as one wheel revolves, it necessarily turns the other; the direction of their motions being indicated by the arrows. The water that enters the lower part of the case is swept up the ends by each cog in rotation, and as it cannot return between the wheels in consequence of the cogs being there always in contact, it must necessarily rise in the ascending or forcing pipe. The machine is therefore both a sucking and forcing Of rotary pumps this is not only one of the oldest, but one of the best. Fire engines made on the same plan were patented about twenty-five years ago England, and more recently pumps of the same kind, in this country. We have one with two elliptical wheels, which were so geared that the longer axis of one wheel might coincide (in one the other. Sometimes a groove is made along the face of each cog, and a strip of leather or other packing secured in it.

one.

seen

The pump figured above is believed to have been known long before Sérviere's time, a model of it, as of other interesting machines, having been placed in his museum without regard to its origin. Ramelli is said to have described some similar ones in the middle of the 16th century, but we have not been able to procure a copy of his book. The suction pipe in the preceding figure has been added. In the original the water entered directly through the bottom of the case: the model was probably so made that part of the wheels might be visible, and the construction and operation of the machine more easily comprehended.

Sérviere was a French gentleman, born at Lyons in 1593. Independent in his circumstances, and inclined to mechanical researches, he was led to establish a cabinet of models of rare and curious machines-of these some were invented by himself and displayed uncommon ingenuity. It does not appear that any account of the whole was ever published; a part only being included in the small volume edited by his grandson, the title of which we have given at the foot of page 63. That work is divided into three parts: the first relates to figures formed in the lathe, as spheres, cubes, ellipses, &c.; some, being hollow and containing others within them, like Chinese balls, are extraordinary specimens of workmanship. There are also vases, urns, &c. not only round and elliptical, but angular, so that not only were the oval and eccentric chucks known to Sérviere, but the lathe for turning irregular surfaces appears to have been used by him. The second part contains an account of clocks all made by himself, the mechanism of which is exceedingly ingenious. Some are moved by springs, others by weights, water, sand, &c. They are fully equal to any thing of the kind at the present day indeed that beautiful device by which a small brass ball is made to traverse backwards and forwards across an inclined plane, which still retains a place among mantel clocks, is one