weight of the bucket and that of the frame: for if B denote the weight of the bucket, F that of the frame, and the force necessary to overcome the friction and the inertia of the pulleys, g denoting 32 feet, t the time occupied in walking up the steps, and s the space ascended or descended, then must B and F be so adjusted as to satisfy the following equation, viz.

S=

B-F
B+F+0

If there be a spring affording but a small quantity of water, or having but a small fall, it is possible by the loss of some of the water to raise the rest to supply a gentleman's seat, or any place where it is wanted; but in a less quantity than what runs waste, if the place to which the water is to be raised is higher than the spring or reservoir from which the water falls. Schottus long ago contrived an engine for this purpose: but the first who put such a thing in execution was Gironimo Finugio, at Rome, in 1616; and the first in this country was George Gerves, a carpenter, who, in the year 1725, erected an engine called the Multiplying-wheel Bucket-engine, at the seat of Sir John Chester, at Chichley, in Buckinghamshire. This engine was much approved by Sir Isaac Newton, Dr. Desaguliers, and Mr., Beighton, and was certainly very ingenious. The water from a spring descended in a large bucket hanging by a cord from an axle, while a smaller quantity was raised from the same place by a cord hanging from a wheel on the same axle: a fly and other regulating apparatus were added, to make the engine work itself, which it did for many years without being out of order. As a whole, however, the contrivance is complex; and we are not aware that any other engines of the same kind have been erected. A description, with a plate, may be seen in Desaguliers' second volume.

12. Mr. H. Sarjeant, of Whitehaven, contrived a very cheap engine for raising water, for which the Society for the Encouragement of Arts awarded him a silver medal in the year 1801. A sketch of this simple invention is given in fig. 215.

This engine was erected at Irton-hall, which is situated on an ascent of 60 or 61 feet perpendicular height: at the foot of this elevation, about 140 yards distant from the offices, there runs a small stream of water; and, in order to procure a constant supply of that necessary fluid, the object was to raise such stream to the house for culinary or domestic uses. With this view, a dam was formed at a short distance above the current, so as to cause a fall of about four feet: the water was then conducted through a wooden trough, into which a piece of leaden pipe, two inches in diameter, was inserted, and part of which is delineated at A.

The stream of this pipe is directed in such a manner as to run into the bucket B, when the latter is elevated; but, as soon as it begins to descend, the stream passes over it, and flows progressively to supply the wooden trough or well, at the foot of which stands the forcing-pump C, being three inches in diameter.

D is an iron cylinder attached to the pump-rod, which passes through it: such cylinder is filled with lead, and weighs about 240 pounds. This power works the pump, and forces the water to ascend to the house through a pipe one inch in diameter, and which is 420 feet in length.

At E is fixed a cord, which, when the bucket approaches to within four or five inches of its lowest projection, extends, and opens a valve in the bottom of the vessel through which the water is discharged.

An engine in a great degree similar to this was erected some years ago

THE OPERATIVE MECHANIC

by the late James Spedding, Esq. for a lead mine near Keswick, with the addition of a smaller bucket which emptied itself into the larger near the beginning of its descent, without which addition it was found that the beam only acquired a libratory motion, without making a full and effective

stroke.

To answer this purpose in a more simple way, Mr. Sarjeant constructed the small engine in such manner as to finish its stroke (speaking of the bucket end) when the beam comes into a horizontal position, or a little below it. By this means the lever is virtually lengthened in its descent in the proportion of the radius to the cosine, of about thirty degrees, or as seven to six nearly, and consequently its power is increased in an equal proportion.

It is evident that the opening of the valve might have been effected, perhaps better, by a projecting pin at the bottom; but Mr. S. chose to give an exact description of the engine as it stands. It has now been some years in use, and completely answers the purpose intended.

The only artificers employed, except the plumber, were a country blacksmith and carpenter; and the whole cost, exclusive of the pump and pipes, did not amount to 51.

In a letter, dated Whitehaven, April 28, 1801, Mr. Sarjeant observes, that the pump requires about 18 gallons of water in the bucket to raise the counter-weight, and make a fresh stroke in the pump; but it makes three strokes in a minute, and gives about a half-gallon into the cistern at each stroke. He adds, "I speak of what it did in the driest part of last summer; when it supplied a large family, together with work-people, &c. with water for all purposes, in a situation where none was to be had before, except some bad water from a common pump, which has been since removed. But the above supply being more than sufficient, the machine is occasionally stopped to prevent wear, which is done by merely casting off the string of the bucket-valve."

13. Mr. Benjamin Dearborn has contrived an hydraulic engine which may be conveniently added to a common pump, and thereby renders it useful in further elevating water, and particularly in extinguishing fires: the following description of his apparatus is extracted from the Memoirs of the American Academy.

Fig. 216. A, B, C, D, represents a pump, the form of which is similar to that of the pumps commonly employed on ship-board.

E, the spout.

F, a stopper.

D, d, a plank-cap, that is fitted to the pump, and provided with leather on its lower surface, being secured by the screws a, b: in the centre is a hole, through which the spear of the pump passes, and round which a leather collar is made, as represented at the letter c.

g, a nut for the screw b.

f, a square piece of wood that is nailed across one end of the plankcap, through both which the screw a is introduced: a hole is made through such piece and the cap that communicates with the bore of the pump.

G, G, a wooden tube, which may be of any requisite length, and consist of any number of joints; it is made square at the lower extremity, and perforated for the reception of the cock; the upper end being made with a nice shoulder.

e, a wooden cock that opens or shuts the communication between the pump and the tube, being furnished on the opposite side with a handle and with a lock, in case it should be found necessary.

h, h, are two ferules, the object of which is to prevent the tube from splitting.

H, H, braces, each of which ought to be crossed over another, as nearly at right angles as possible.

i, i, are irons in form of a staple, which surround the tube, and pass through the braces; their ends being perforated with holes for fore-locks.

K, L, M, N, is a head made of five pieces of wood; k, l, m, n, a square piece, in the lower part of which is a hole for the reception of the extremity ef the tube, and which piece rests on the shoulder o, p; to the lower end of this head is nailed a piece of leather, with a hole in its centre, similar to that made in the wood. Another piece of leather of the same form is placed on the top of the tube, and between both is a circle of thin platebrass; the two pieces of leather and the brass being pressed between the lower end of the head and the shoulder of the tube. Their edges are delineated at o, p.

K, N, and L, M, are the edges of two pieces of plank, of a similar width with the head, to which they are closely nailed, each being provided with a tenon, that passes through a mortice in the end of the piece.O, P: both tenons have holes for a fore-lock at q.

O, P, a piece of plank of the same width as the sides; the centre of which is perforated, in order that the tube may pass through; and in each end of which is a mortice for the reception of the tenons.

N, M, a cap.

r, r, are two pieces nailed to the side of the tube; the lower extremity of each is provided with a truck, with a view to lessen the friction of the head in its horizontal revolution.

q, q, represent fore-locks, the design of which is to fasten down the head, and prevent the water from escaping at the joint o, p.

Q, R, is a wooden conductor: the extremity marked with the letter Q being solid, while the opposite end, R, is bored with a small auger.

8, a bolt that passes through the conductor and head, and being secured on the back with a fore-lock or nut: this bolt is rounded near the head, and square in the middle.

t, u, w, z, represents a piece of iron or brass, designed to prevent the head of the bolt from wearing into the wood.

S, S, are ropes for the direction of the conductor.

Fig. 217 represents the head without such conductor.

a, b, c, d, is a thick brass plate, the centre of which is perforated, so as to admit a passage to impurities, that might otherwise obstruct the conductor: for which purpose a piece of leather is nailed under it to the head. The square hole in the centre is adapted to the size of the bolt, which it prevents from turning. The conductor has a hollow cut round the bolt on the inside, of the same size as the circle of holes in the brass; round such cavity is nailed, on the face of the conductor, a piece of leather, that plays on the margin of the brass plate when the conductor is in motion.

In the conclusion of his memoir, Mr. Dearborn observes, that he has raised a tube of 30 feet on his pump; and, though the severity of the season had prevented him from completing it, so that one person only could work at the brake, yet he is enabled to throw water on a contiguous building, the nearest part of which is 37 feet from the pump, and between 30 and 40 feet in height.

14. Archimedes' Screw, or the Spiral Pump, or, as it is called in Germany, the Water-snail, is a machine for the raising of water, first invented by Archimedes.

Its structure and use will be understood by the following description of it.

Fig. 218. A, B, C, D, is a wheel, which is turned round, according to the order of the letters, by the fall of water E F, which need not be more than three feet. The axle G of the wheel is elevated so as to make an angle of about 44o, or between 45o and 60o, with the horizon; and on the top of that axle is a wheel H, which turns such another wheel I of the same number of teeth; the axle K of this last wheel being parallel to the axle G of the two former wheels. The axle G is cut into a double-threaded screw, fig. 219, exactly resembling the screw on the axis of the fly of a common jack, which must be what is called a right-handed screw, like the wood screws, if the first wheel turns in the direction A BCD; but it must be a left-handed screw, if the stream turns the wheel the contrary way; and the screw on the axle G must be cut in a contrary way to that on the axle K, because these axles turn in contrary directions.

These screws must be covered close over with boards, like those of a cylindrical cask; and then they will be spiral tubes. Or they may be made of tubes of stiff leather, and wrapped round the axles in shallow grooves cut therein, as fig. 220. The lower end of the axle G turns constantly in the stream that turns the wheel, and the lower ends of the spiral tubes are open unto the water. So that, as the wheel and axle are turned round, the water rises in the spiral tubes, and runs out at Q, through the holes M N, as they come about below the axle. These holes, of which there may be any number, as four or six, in a broad close ring on the top of the axle, into which ring the water is delivered from the upper open ends of the screw tubes, and falls into the open box N. The lower end of the axle K turns on a gudgeon, in the water N; and the spiral tubes in that axle take up the water from N, and deliver it into another such a box under the top of K; on which there may be such another wheel as I, to turn a third axle by such a wheel upon it. And in this manner water may be raised to any given height, where there is a stream sufficient for that purpose to act on the broad float-boards of the first wheel.

15. Another kind of engine, called the Pressure Engine, several of which have been lately erected in different parts of the country, is used for raising water by the pressure and descent of a column enclosed in a pipe. The principle was first adopted in France, in some machinery erected about 1731, and is described by Belidor, in his Arch. Hydraul. lib. iv. ch. 1. But the engine we are now going to describe is the invention of Mr. Trevitheck, who probably was not aware that one of a similar nature had been before attempted. It was erected about thirty years ago at the Druid Copper-mine, in the parish of Illogan, near Truro.

A section of it is given in Fig. 221.

A B represent a pipe six inches in diameter, through which water descends from the head to the place of its delivery to run off by an adit at S, through a fall of 34 fathoms in the whole; that is to say, in a close pipe down the slope of a hill 200 fathoms long, with 26 fathoms fall, then perpendicularly

six fathoms till it arrives at B, and thence through the engine from B to S. two fathoms. At the turn B the water enters into a chamber C, the lower part of which terminates in two brass cylinders, four inches in diameter; in which two plugs or pistons of lead, D and E, are capable of moving up and down by their piston-rods, which pass through a close packing above, and are attached to the extremities of a chain leading over and properly attached to the wheel Q, so that it cannot slip.

The leaden pipes D and E are cast in their places, and have no packing, whatever. They move very easily; and if at any time they should become loose, they may be spread out by a few blows with a proper instrument, without taking them out of their place. On the sides of the two brass cylinders in which D and E move, there are square holes communicating towards F and G, which is a horizontal trunk or square pipe, four inches wide and three inches deep. All the other pipes G, G, and R, are six inches in diameter, except the principal cylinder wherein the piston H moves; and this cylinder is ten inches in diameter, and admits a nine-foot stroke, though it is here delineated as if the stroke were only a three-foot.

The piston-rod works through a stuffing-box above, and is attached to M N, which is the pit-rod, or a perpendicular piece divided into two, so as to allow its alternate motion up and down, and leave a space between, without touching the fixed apparatus or great cylinder. The pit-rod is prolonged down into the mine, where it is employed to work the pumps, or if the engine were applied to mill-work, or any other use, this rod would form the communication of the first mover.

K L is a tumbler, or tumbling-bob, capable of being moved on the gud, geon V, from its present position to another, in which the weight L shall hang over the same inclination on the opposite side of the perpendicular, and consequently the end K will then be as much elevated as it is now depressed.

The pipe RS has its lower end immersed in a cistern, by which means it delivers its water without the possibility of the external air introducing itself; so that it constitutes a torricellian column, or water barometer, and renders the whole column from A to S effectual: as we shall see in our view of the operation.

Let us suppose the lower bar K V of the tumbler to be horizontal, and the rod PO so situated, as that the plugs or leaden pistons D and E shall lie opposite to each other, and stop the water-ways G and F. In this state of the engine, though each of these pistons is pressed by a force equivalent to more than 1000 pounds, they will remain motionless, because these actions being contrary to each other, they are constantly in equilibrio. The great piston H being here shown as at the bottom of its cylinder, the tumbler is to be thrown by hand into the position here delineated. Its action upon OP, and consequently upon the wheel Q, draws up the plug D, and depresses E, so that the water-way G becomes open from A B, and that of F to the pipe R: the water consequently descends from A to C; thence to GGG, until it acts beneath the piston H. This pressure raises the piston, and if there be any water above the piston, it causes it to rise and pass through F into R. During the rise of the piston (which carries the pit-rod MN along with it) a sliding block of wood I, fixed to this rod, is brought into contact with the tail K of the tumbler, and raises it to the horizontal position, beyond which it oversets by the acquired motion of the wheel L.

The mere rise of the piston, if there were no additional motion in the tumbler, would only bring the two plugs D and E to the position of rest, namely, to close G and F, and then the engine would stop; but the fall of the tumbler carries the plug D downwards quite clear of the hole F, and