Chap. 5.]

Rotary Pumps.

291

drum or case, to which an ascending or forcing pipe is attached: the water would rise through the pipe, provided the velocity of the arms was increased according to the elevation of its discharging orifice. In place of tubular arms, two or more vanes radiating from a vertical axis and turned rapidly in the case would produce the same effect; the suction pipe being connected to the bottom at the centre and the forcing pipe to the rim or the top. Such pumps are in their construction simpler than other rotary ones, besides which no particular accuracy is required in fitting their working parts; nevertheless, they are as liable to derangement as others, for the velocity required to be given to the arms is so great, that the teeth of the wheels and pinions by which motion is transmitted to them

are soon worn out.

Centrifugal pumps like those just described have been tried as substitutes for paddle wheels of steam-vessels: i. e. the wheels were converted into such pumps by inclosing them in cases made air-tight, except at the bottom through which the ends of the paddles slightly projected; a large suction pipe proceeded from one side of each case (near its centre) through the bows of the vessel and terminated below the water line: by the revolution of the wheels water was drawn through these tubes into the cases and forcibly ejected below in the direction of the stern, and by

the reaction moved the vessel forward.

It must not be supposed that the preceding observations include an account of all rotary pumps. We have only particularized a few out of a great multitude, such as may serve as types of the various classes to which they belong. Were a detailed description given of the numerous forms of these machines, modes of operation, devices for opening and closing the valves, moving the pistons, diminishing friction, compensating for the wear of certain parts, for packing the pistons, &c. &c., those readers who are not familiar with their history would be surprised at the ingenuity displayed, and would be apt to conclude that all the sources of mechanical combinations had been exhausted on them. We would advise every mechanic who thinks he has discovered an improvement in rotary pumps, carefully to examine the Repertory of Arts, the Transactions of the Society of Arts, the London Mechanics' Magazine, and particularly the Journal of the Franklin Institute of Pennsylvania, before incurring the expenses of a patent, or those incident to the making of models and experiments.

Rotary pumps have never retained a permanent place among machines for raising water: they are, as yet, too complex and too easily deranged to be adapted for common use. Theoretically considered they are perfect machines, but the practical difficulties attending their construction have hitherto rendered them (like rotary steam engines) inferior to others. To make them efficient, their working parts require to be adjusted to each other with unusual accuracy and care, and even when this is accomplished, their efficiency is, by the unavoidable wear of those parts, speedily diminished or destroyed: their first cost is greater than that of common pumps, and the expense of keeping them in order exceeds that of others; they cannot, moreover, be repaired by ordinary workmen, since peculiar tools are required for the purpose-a farmer might almost as well attempt to repair a watch as one of these machines. Hitherto, a rotary pump has been like the Psalmist's emblem of human life :-" Its days are as grass, as a flower of the field it flourisheth, the wind [of experience] passeth over it, and it is gone." Were we inclined to prophecy, we should predict that in the next century, as in the present one, the cylindrical pump will retain its preeminence over all others; and that makers of the ordi

292

Reciprocating Rotary Pumps.

[Book III. nary wooden ones will then, as now, defy all attempts to supersede the object of their manufacture.

RECIPROCATING ROTARY PUMPS :-One of the obstacles to be overcome in making a rotary pump, is the passage of the piston over the butment, or over the space it occupies. The apparatus for moving the butment as the piston approaches to or recedes from it, adds to the complexity of the machine; nor is this avoided when that part is fixed, for an equivalent movement is then required to be given to the piston itself in addition to its ordinary one. In reciprocating rotary pumps these difficulties are avoided by stopping the piston when it arrives at one side of the butment and then reversing its motion towards the other; hence these are less complex than the former: they are, however, liable to some of the same objections, being more expensive than common pumps, more difficult to repair, and upon the whole less durable. Their varieties may be included in two classes according to the construction of the pistons; those that are furnished with valves forming one, and such as have none the other. The range of the pistons in these pumps varies greatly; in some the arc described by them does not exceed 90°, while in others they make nearly a complete revolution. They are of old date, various modifications of them having been proposed in the 16th century. No. 139 consists of a close case of the form of a sector of a circle, having an opening at the bottom for the admission of water, and another to which a forcing pipe with its valve is attached. A movable radius or piston is turned on a centre by a lever as represented; thus, when the latter is pulled down towards the left, the former drives the contents of the case through the valve in the ascending pipe.

No. 139.

No. 140.

Belidor has described a similar pump in the first volume of his Arch. Hydraul. 379. The case is a larger portion of a circle than that of No. 139, and the piston is furnished with a valve. A pump on the same principle was adopted by Bramah as a fire-engine in 1793: His was a short cylinder, to the movable axle of which two pistons were attached that extended quite across, and had an opening covered by a clack in each.

No. 140 consists of a short horizontal cylinder: a portion of the lower part is separated from the rest by a plate where the suction pipe terminates in two openings that are covered by clacks c c. The partition A

Chap. 6.]

Application of Pumps in Modern Water-works.

293

extends through the entire length of the cylinder and is made air and water tight to both ends, and also to the plate upon which its lower edge rests. The upper edge extends to the under side of the axle to which the piston B is united. One end of the axle is passed through the cylinder and the opening made tight by a stuffing box; it is moved by a crank or lever. Near the clacks cc two other openings are made through the plate, to which two forcing pipes are secured. These tubes are bent round the outside of the cylinder and meet in the chamber C where their orifices are covered by clacks. Thus when the piston is turned in either direction, it drives the water before it through one or other of these tubes; at the same time the void left behind it is kept filled by the pressure of the atmosphere on the surface of the liquid in which the lower orifice of the suction pipe is placed. The edges of the pistons are made to work close to the ends and rim of the cylinder by means of strips of leather screwed to them. Modifications of these pumps have also been used in England as fire-engines.

Reciprocating rotary pumps have sprung up at different times both here and in Europe, and have occasionally obtained" a local habitation and a name," but have never become perfectly domesticated, we believe, in any country. We have seen some designed for ordinary use that were elegantly finished, and decorated with gilding and japan-they resembled those exotic plants which require peculiar care, and are rather for orna

ment than for use.

Reciprocating rotary pumps have also been proposed as steam-engines. Watt patented one in 1782.

CHAPTER VI.

APPLICATION of pumps in modern water-works: First used by the Germans-Water-works at Augsburgh and Bremen-Singular android in the latter city-Old water-works at Toledo-At London bridge -Other London works moved by horses, water, wind and steam-Water engine at Exeter-Waterworks erected on Pont Neuf and Pont Notre Dame at Paris-Celebrated works at Marli-Error of Rannequin in making them unnecessarily complex. American water-works: A history of them desirableIntroduction of pumps into wells in New-York city-Extracts from the minutes of the Common Council previous to the war of Independence-Public water-works proposed and commenced in 1774-Treasury notes issued to meet the expense-Copy of one-Manhattan Company-Water-works at Fair Mount, Philadelphia.

to

BEFORE noticing another and a different class of machines, we propose occupy this and the two next chapters with observations on the employment of pumps in "water-works," and as engines to extinguish fires -both in this country and in Europe.

The hydraulic machinery for supplying modern cities with water generally consists of a series of forcing pumps very similar to the machine of Ctesibius, (No. 120;) and when employed to raise water from rapid streams, or where from tides or dams a sufficient current can be obtained, are worked like it by under or by overshot wheels. An account of old European water-works is an important desideratum, for it would throw light on the history of pumps in the middle ages, during which little or nothing respecting them is known. The older cities of Germany were the first in modern days that adopted them to raise water for public purposes; but of their construction, materials, and application under various circum stances, we have no information in detail. Rivius, in his Commentary on

294

Pump Engines in Germany.

[Book III. the machine of Ctesibius, speaks of pumps worked by water wheels as then common, (A. D. 1548.) The hydraulic engines at Augsburgh were at one time greatly celebrated. They are mentioned, but not described, by Misson and other travelers of the 17th century. They raised the water 130 feet. Blainville, in 1705, speaks of them as among the curiosities of the city. He observes-"The towers which furnish water to this city are also curious. They are near the gate called the Red Port, upon a branch of the Leck which runs through the city. Mills which go day and night, by means of this torrent, work a great many pumps, which raise water in large leaden pipes to the highest story in these towers. In the middle of a chamber on each of them, which is very neatly and handsomely ceiling'd, is a reservoir of a hexagonal figure, into which the water is carried by a large pipe, the extremity of which is made like a dolphin, and through an urn or vase held by a statue sitting in the middle of the reservoir. One of these towers sends water to all the public fountains by smaller pipes, and the three others supply with water a thousand houses in the city; each of which pays about eight crowns yearly, and receives a hundred and twenty pretty large measures of water every hour." Travels, vol. i, 250. Misson's Travels, 5 ed. vol. i, 137.

Contemporary with the engines at Augsburgh was one at Bremen that is mentioned by several writers of the 17th century. It was erected on one of the bridges and moved by a water wheel: it raised water into a reservoir at a considerable elevation, whence the liquid was distributed to all parts of the city. An old author when speaking of it, mentions an android in Bremen, a species of mechanism for which the Germans were at one time famous. At the entrance of the arsenal, he observes, stands the figure of a warrior arm'd cap-a-pe, who, by mechanism under the steps, as soon as you tread on them, lifts up the bever of his helmet with his truncheon to salute you."

There was also a celebrated water-engine at Toledo, the former capital of Spain. It raised the water of the Tagus to the top of the Alcazar, a magnificent palace erected on the summit of the declivity on which the city. is built; the elevation being "five hundred cubits from the surface of the river." What the particular construction of this machine was we have not been able to ascertain, nor whether it was originally erected by the Moors who built the palace. It is mentioned by Moreri as a "wonderful hydraulic engine which draws up the water from the river Tagus to so great a height, that it is thence conveyed in pipes to the whole city;" but in the middle of the last century (1751) the author of the Grand Gazetteer, or Topographic Dictionary, remarks (page 1289) that this “admirable engine" was then "entirely ruined."

The introduction of pump engines into the public water-works of England and France is sufficiently ascertained. This did not take place till long after they had been employed in Germany; and both London and Paris were indebted to engineers of that country for the first machines to raise water from the Thames and the Seine. Previous to their introduction, cities were commonly supplied from springs by means of pipes. As early as A. D. 1236, the corporation of London commenced to lay a six inch leaden pipe from some springs at Tyburn, a village at that time some miles distant from the city. This is supposed to have been the first attempt to convey water to that city through pipes, and fifty years elapsed before the whole was completed. These pipes were formed of sheet lead and the seams were soldered: part of them was accidentally discovered in 1745 while making some excavations, and another portion in 1765. (London Mag. for 1765, p. 377.) In 1439 the abbot of Westminster, in whom

Chap. 6.]

London Water-works.

295

the right of the soil was vested, granted "to Robert Large the mayor and citizens of London, and their successors, one head [reservoir] of water, containing twenty-six perches in length and one in breadth, together with all its springs in the manor of Paddington: in consideration of which grant, the city is for ever to pay to the said abbot or his successors, at the feast of St. Peter, two pepper corns." This grant was confirmed by Henry VI, who at the same time authorized the mayor and citizens, by a writ of the privy seal, to purchase two hundred fothers of lead "for the intended works of pipes and conduits, and to impress plumbers and labourers.” Maitland's Hist. of London, pp. 48, 107.

In the 33d year of Henry VIII, the mayor of the city of Glocester, with the dean of the church there, were authorized to " convey water in pipes of lead, gutters and trenches" from a neighbouring hill, "satisfying the owners of the ground there for the digging thereof."a In the following year, the mayor and burgesses of Poole were authorized to erect a wind mill on the king's waste ground, and a conduit head sixteen feet square, "and to dig and draw [water] in, by, through and upon all places meet and convenient, into and from the same, &c.-yielding yearly to the king and his heirs one pepper corn." It would appear that the reservoir was in too low a situation for its contents to flow through pipes to the town, and hence the wind mill to raise it sufficiently for that purpose. The machine used was probably the chain of pots, which, as remarked page 125, was at that time often employed in such cases. In the 35th of Henry VIII, the corporation of London was authorized to draw water through pipes from various villages and other places within five miles of the city, and for this purpose to enter any grounds not enclosed with "stone, brick or mud walls, and there to dig pits, trenches and ditches; to erect heads, lay pipes, and make vaults and suspirals," &c. Two years afterwards, (A. D. 1546,) a law was passed by which those who destroyed conduit heads and pipes, were put to death. In 1547, William Lamb conveyed water in a leaden pipe from a conduit or spring, which still bears his name.d

In 1582, the first pump machines were used in London. In that year Peter Maurice, a German engineer, proposed to erect a machine on the Thames for the more effectual supply of the city," which being approved of, he erected the same in the river near London bridge, which by suction and pressure, through pumps and valves, raised water to such a height as to supply the uppermost rooms of the loftiest buildings, in the highest part of the city therewith, to the great admiration of all. This curious machine, the first of the kind that ever was seen in England, was so highly approved of, that the lord mayor and common council, as an encouragement for the ingenious engineer to proceed in so useful an undertaking, granted him the use of one of the arches of London bridge to place his engine in, for the better working thereof."e Maurice's engine consisted of a series of forcing pumps (similar to Nos. 118 and 121) seven inches in diameter, and the pistons had a stroke of thirty inches; they were worked by an undershot wheel that was placed under one of the arches and turned by the current, during the rise and fall of the tide; the water was raised to an elevation of 120 feet. The number of pumps and wheels was subsequently increased; but in 1822, when the old bridge was taken down, the whole were removed.f

Two years before Maurice undertook to raise water from the Thames, Stow says "One Russel proposed to bring water from Isleworth, viz: Statutes at large. Lon. 1681. b Ibid. Ibid. d Maitland, 158. e Ibid. 160. A description of the London Bridge Water-works, by Beighton, may be seen in the Philos. Trans. vol. vi, 358, and in Desaguliers' Philos. ii, 436.

c