N, opening on its way the upper or delivery-valve, which is enclosed in the valve-box, O; therefore it is assumed that the water is raised to the barrel by atmospheric pressure, and is then ejected or discharged by the force acting on the bucket or piston, as applied by means of the lever B.

There is, so to speak, a species of condition attached to this pump, which is, that the bucket, in theory, must not rise more than thirty-two feet above the surface of the water; but in practice twenty-eight feet is usually found to be the maximum.

When the well is more than

FIG. 40.

thirty feet deep (unless a deep-well pump be used), it is necessary to have detached barrels, which are placed down the well within from fifteen to twenty feet of the water; "rising main-pipes" are then placed between the detached barrel in the well and the pump-head at the surface, which must be large enough to allow the bucket to pass freely down to the detached working barrel. This is a very good arrangement of pumps for wells not exceeding seventy feet in depth.

It is obvious that the height to which the water is thrown will depend upon the amount of power applied to the lever, or pump-brake, as it is sometimes called. In small pumps employed for domestic or household purposes, the strength of a man as the motive power is ordinarily exerted; but in raising water from great depths, such as from the bottoms of mines, &c., a steam-engine becomes absolutely necessary. In steampumps the arrangement is usually what is known among practical men as the bucket and plunger principle, or else double-acting, i.e., throwing a stream of water both in the up and down stroke. A feed-pump, with a plunger in lieu of a bucket, for feeding steamboilers, is shown by Fig. 40. This is usually worked off an eccentric fixed on the engineshaft.

THE FIRE-ENGINE.

One of the most useful modifications of the force-pump is the machine known familiarly enough to us as the fire-engine. It is in reality only an arrangement of two or more force-pumps (the number varying proportionately according to the size of the engine), mounted on a carriage or framing, and whose buckets are worked by a long rod passing through the ends of a lever with equal arms, each lever having a common fulcrum. The engine is fitted with one or more suction-pipes common to both pumps, and possessing one or more delivery-pipes (the number varying with the size of the pumps), which discharge the jet of water through the hoses which are attached to them. An air-vessel is indispensable for this class of pumping machinery, in order to keep up the continuous stream of water so necessary for its efficient working.

Fig. 41 is a diagram which will be found amply sufficient to give the reader a general idea of the action of one of the most invaluable inventions--socially speaking-in hydraulic machinery. I will give a brief description of the diagram. A, buckets; B, barrels; C, fulcrum of lever, D; E, air-vessel; F, suction-pipe; G, delivery-pipe or hose; H, suction-valves; I, delivery-valves.

A great improvement has taken place within the last few years in the manufacture of this class of machinery, steam power being now very extensively used in lieu of the hard labour involved by manual power. Soon the hand fire-engines will be things of the past, and only to be seen in small towns or factories. In the steam fire-engines steam is frequently got up while proceeding from the engine station to the fire, and may be got up from cold water in very little over ten minutes.

Fig. 42 shows some of the various forms of valves used in pumps. a is called the flap; b, rising and falling; c, ball-clack; d, clack; e, circular Indiarubber valve for air-pumps, &c.

THE CENTRIFUGAL PUMP.

This is a very powerful and ingenious machine, and was invented by the late Mr. Appold. Its capabilities were very severely tested at the Great Exhibition of 1851, where it obtained the council medal, a silver medal in 1855 at Paris, and prize medal at the International Exhibition of 1862. It is now used in most places where large quantities of water or other fluids are required to be raised to a moderate height. It is also most admirably adapted for drainage purposes, several very large pumps having been recently erected for that purpose, both here and abroad. The speed at which each pump is driven varies with the lift and also with each size of pump. On referring to Fig. 43 (showing a front and side elevation), it will be seen that the pump-case and water-passages are cast in one piece, so that by taking off the cover, C, and

the blank flange, D, all the working parts may be removed in a few minutes. The principle of this pump is as follows: a hollow fan or disc, E (somewhat similar to a small water-wheel), revolves at a high speed inside the case. This

has the effect of sucking up the water into the top part of the case, whence it is discharged in a considerable stream. This pump will pass anything that is small enough to go through, there being no small valves; in fact, there is only the foot-valve, which is a large flap-valve. A quantity of nut-galls have been thrown into a medium size pump all at once, when it was running at a high speed, and they passed out of the delivery-pipe without a single one being

broken.

THE HYDRAULIC RAM OR WATER-ENGINE.

In building a house, or buying a farm, the first consideration is a good supply of water. This may be obtained with comparative ease by aid of this engine.

There are numbers of important places, such as private estates, mansions, railway stations, public institutions, and the like, where, instead of depending on servants who invariably dislike the job-for pumping a supply of water for the establishment, and in many cases going to great expense in sinking wells and providing pumping-gear, it is quite practicable, by simply making use of a small stream in the immediate vicinity, to obtain an abundant and constant supply, sufficient for the house, garden, or stables, &c. The height to which this machine will raise the water is proportionate to the fall that can be obtained in the length of injection-pipe leading from the stream to the ram; but it may be taken as a rule that the water will be driven up twelve times the height of the head; .g., a fall of three feet in the induction-pipe will maintain

a percussive action on the ram sufficient to force the water in moderate quantities to the height of thirty-six feet, and so on. Many of these engines havo been in operation for several years with great success, and have invariably given great satisfaction. They will raise from 1,000 to 3,000 gallons per day of twenty-four hours from 50 ft. to 250 ft. high, according to size.

The essential parts of the machine are as follows: the water enters by the incline injection-pipe, A, and acquires sufficient impetus to force a portion through a valve in valve-box, B (the surplus running to waste through the overflow or relief-valve, E) into the air-vessel, C. The condensed air in the upper part of C causes the water to rise in the delivery-pipe, D, as long as the effect of the water on A E continues.

SHIP-BUILDING AND RIGGING.

To cut out a model of a ship from a block of wood may seem at first sight an easy affair. To one who knows how to do it the task is, of course, not difficult, though for its proper execution a considerable amount of care and nicety is required. A rough specimen of a ship-one that will float, at all eventsmay be hewn out of a block by any one having an accurate eye and a ready hand; but little good can be done by guess-work, which such sort of work must necessarily be, and certainly no preconceived design can be executed by its aid. It is the object of this article to furnish the means by which not only can a model be cut out of a block of wood, but be also actually built, dockyard fashion, in exact accordance with the design which we will suppose the amateur to have formed for himself.

The modeller, having decided in his own mind upon the form of the vessel he intends to build or cut out, must then draw out the design on paper. He must fix not only the character and class of vessel, as ship, brig, schooner, or whatnot; he must also settle with himself as to the "lines" upon which she shall be constructed; that is to say, he must decide upon the precise shape she shall have. Let us suppose that he intends to make a schooner yacht. The side elevation, or, as it is called, the "sheer plan," is drawn as in the annexed engraving (Fig. 1), and is divided into as many divisions as it is proFosed to have variations in the external form of the hull. The line at the place where the greatest breadth of beam is to be is marked with *, and is called the "dead flat;" the lines marked respectively A, B, C, D, show the places at which the external form of the hull forward is meant to be altered; the lines marked 1, 2, 3, 4, 5, show the places at which the external shape of the hull aft is to be modified. The second figure in the engraving shows the design of half the deck, and has the divisions also marked upon it. At the bottom of the plate is a drawing showing the form of the ship's side and bottom, from the deck to the keel, and this drawing is part of the design which must be decided on beforehand. The outermost form corresponds with the plan of the half-deck sketched out above; and the other forms show the intended shape at the lower sections. The drawing is, in fact, a drawing of half the vessel bottom upwards.

Upon a copy (on paper or wood) of the sheer plan are drawn horizontal lines parallel with the keel, the number of them agreeing with the number of different water-lines or shapes in the design. On another piece of paper are drawn a similar set of parallel lines; a perpendicular line being drawn upon the bottom one, is taken to represent the centre of the transverse section of the ship. The object now is to get an elevation of the forms of the bow and stern. On the topmost of this set of lines (see figures at top and bottom of the engraving) mark off, to the left of the central perpendicular, the half-breadths of each of the forward divisions, as given in the half-breadth section at the bottom of the engraving; and on to the top line, to the right of the central line, the half-breadths of the after divisions. On the line corresponding to the number or letter of the half-breadth plan mark off the distance between the centre and the outer edge of each line of form as there displayed, and