and boiler, has a capacity of two-thirds of a second-foot. The operation of this plant calls for the consumption of about 1 cord of wood per day of twenty-four hours, and it is capable of irrigating about 3 acres in a season. A similar pump in the same locality and operated by a gasoline engine of 35 horsepower will handle about 11 acre-feet in twenty-four hours on a consumption of about 84 gallons of gasoline. Other centrifugal pumps of small capacities and capable of watering 5 to 10 acres per day, and in the course of an irrigation season from 50 to 100 acres, are operated by one man at a cost of about $2.50 per acre irrigated for maintenance and $15 per acre for first cost of plant.

It is proposed to erect an extensive centrifugal pumping plant for the Summit Lake Water Company in California, and the estimates of the engineers for a plant capable of irrigating 40,000 acres, including distributing canals and other items, is $81,000, the cost of the pumping plant alone being estimated at about 75 cents per acre, while the cost for operation of and interest on the pumping plant during an irrigating season is estimated to be about $1 per acre, on the assumption that the depth of irrigation will be 1 foot and the lift 20 feet. These figures are considerably below those of most gravity systems.

Rotary pumps, while theoretically the most efficient, are practically capable of elevating but small quantities of water, and have been found of small value in elevating water for irrigation. They may be termed revolving-piston pumps in distinction from direct-action pumps, and have the advantage of not changing the direction of flow of water during its elevation by each stroke of the pump. They can be run at high speed, and have no complicated leather valves or pistons to be choked or otherwise get out of order. They are probably most useful in lifting silt-laden water or heavy fluids. There are numerous forms of these pumps in the market. A large machine of this type, made by the National Pump Company, is stated to be capable of lifting about 5 acre-feet of water in twenty-four hours to a height of 20 feet on an expenditure of about 5 horsepower, and to a height of 100 feet on an expenditure of 25 horsepower. The first cost of this machine is $400, or about $150 per second-foot. The efficiency of rotary pumps is low, there being an excess in driving power required over effective work performed.

MECHANICAL AND SIPHON ELEVATORS.

There are several varieties of mechanical water elevators, nearly all of which act on the principle of an endless chain carrying buckets. This endless chain revolves on two wheels, one at the upper end of the lift and one beneath the surface of the supplying well or stream. As the chain revolves, the buckets dip into the water and become filled, and as they reach the upper end of their revolution they spill their contents into a trough which leads it to the irrigating ditches. Two of the more popular patented varieties of mechanical water elevators are

the link-belt box water elevator and the Seaman irrigating pump. The link-belt box elevator consists of an elongated box which is set up in an inclined position over the water supply, at either end of which is a wheel of peculiar construction carrying on its periphery a metal link belt or chain, attached to which at short intervals are wooden projections of such dimensions as to fill the cross-section of the box. As the chain travels forward these projections are raised, carrying with them the water resting upon them until it reaches the upper end of the box, where it is discharged into the irrigating ditch. This machine may be operated by animal, steam, or water power, and the largest sizes are capable of lifting about 5 second-feet with an expenditure of 7 horsepower for a 10-foot lift. The highest practicable lift of these machines is 20 feet, and one of this capacity costs $50 per second-foot. The Seaman irrigating pump is similar to the apparatus just described, excepting that instead of a series of wooden flights or projections lifting water in a closed box it consists of a number of large galvanized iron buckets carried by the chain working in the open, the buckets being closed on all sides, with the exception of an opening on the bottom containing a ball valve retained by a little wire basket. When the bucket is filled the ball is pressed down in the basket so as to close the opening, and as the bucket reaches the upper part of its revolution the ball drops in the basket, permitting the water to flow out freely. The largest of these contrivances are capable of lifting about 1 second-feet on an expenditure of 5 horsepower, the first cost being about $250.

There is manufactured in France, by Lemichel et Cie, an apparatus called a siphon elevator, which is claimed to attain an efficiency of 90 per cent. It consists of a siphon erected at a fall or dam in a river, at a reservoir dam, or in any situation where the lower discharge arm can be carried below the suction pipe so as to give a difference of elevation for the creation of siphon action. At the highest point of the siphon are constructed air and valve chambers, the effect of which is to relieve the siphon at that point of part of the water passing through it, only a portion passing on down through the longer arm of the siphon to keep up siphon action. It is this contrivance which enables water to be elevated by the siphon to heights as great as nearly 30 feet at sea level, instead of being delivered, as by common siphons, below the point from which it is derived.

The siphon elevator (fig. 17) depends for its efficiency on the opera tion of the air chamber or receiver and the regulator, which are placed at the upper bend of the siphon pipe. At the bottom of the suction. pipe is a check valve which allows the ingress of water but prevents its escape. At the bottom of the lower arm of the siphon is a stopcock which, when open, permits the escape of water, so that when it moves a vacuum is created behind it, which is filled with water, as in simple siphons. In action the siphon elevator must first be filled with.

water, and as this descends in the lower pipe and ascends in the upper or suction pipe it passes through the receiver (a), where it reaches an open check valve which intermittently cuts off its flow into the regulator (b). The water forces this valve (c) forward until shut, and, its exit being thus cut off, its momentum raises a puppet valve (d) in the receiver held down by a spiral spring. Through this valve the water escapes into a storage tank or irrigating ditch. While the regulator is being partially emptied into the pipe a vacuum is caused, which creates a depression in the corrugated heads of the regulator, as in an aneroid barometer, and the pressure on the clack valve (c) being diminished, it is thrown open by a weight on a lever, permitting the water to fill the regulator once more and the corrugated heads to again assume their normal position. This vibratory motion occupies but a brief time, as many as 150 to 400 such pulsations taking place per minute, so that the flow of water is nearly continuous.

The capacity of these siphon elevators varies according to their dimensions and the height to which they elevate the water, but at sea level they have been built with capacities sufficiently great to elevate 8 acre-feet in twenty-four hours. This is a very large quantity when the simplicity of construction and cheapness of first cost of this mechanism-about $1,200-are considered; and it may be safely stated that if further experiment with it shows it to be as effective as claimed in the past, it will be a valuable water-lifting apparatus where only trifling heights-say 10 to 15 feet-are to be overcome and there is sufficient fall and surplus water to permit of the wastage caused by the operation of the siphon. Batteries of two or three of these siphon elevators have been erected, one above the other, whereby, with additional wastage of water for each siphon, heights two or three times those to be effected by one siphon elevator have been obtained.

STORAGE RESERVOIRS.

The storage reservoir or tank employed to retain water which has been pumped when not required for irrigation should be situated at the highest point on the irrigable land. When there is but little slope to the land it may be impracticable to build an earth reservoir at a sufficient elevation to obtain a good head, in which case a wooden or metal tank should be used. Such tanks can be gotten from any of the windmill makers, and range from 10 to 30 feet in diameter, their depths varying between 3 and 20 feet and their capacities from 1,000 gallons upward. These tanks (Pl. II, p. 30), when constructed of wood, are made of the best selected clear pine and are bound by from 3 to 20 iron hoops, depending on the dimensions of the tank. Their prices range from $30 to $800 each.

Where artificial reservoirs can be constructed on the land, it is best, provided suitable material for rendering them impervious can be found, to build them up by constructing about the reservoir an embankment rather than by making an excavation in the ground. The reason for this is that the former mode of construction places the water surface at some height above the ground level and, besides making a larger volume of the water supply available, gives a better head for flowing it through the ditches. The most economical way in which to construct such reservoirs is to find a gully or depression of some sort in one of the higher portions of the land and build across the lower end of this an earth embankment. This is rarely possible on the level plains, where it is necessary to wholly surround the basin by an artificial embankment.

For the latter type of reservoir the best shape is circular, as such is more easily built and has a larger capacity for the same amount of material moved (Pl. IV, p. 34). The ground should first be deeply plowed and stripped of the surface soil, and this loose material be used as a portion of the outer face of the inclosing embankment. The crosssection of the latter should be rather flat, its slopes depending upon. the nature of the soil. Where a firm, clayey gravel can be obtained, free of vegetable mold and other foreign substances, this will make one of the most impervious embankments. It may be given a cross-section as steep as about 13 horizontal to 1 vertical on the inside, and about 2 horizontal to 1 vertical on the outside, with a top width of not less than 4 feet. For less suitable material, as more sandy soil, or that containing some admixture of loam, flatter slopes must be used, reaching even as low as 3 horizontal to 1 vertical inside, and 3 or 4 to 1 on the outside. In every case such an embankment should be built up in horizontal layers, well and deeply bonded with the subsurface soil, these layers not exceeding 6 inches in thickness and being separately tramped by animals or rolled by heavy rollers as laid. If there is available a gravel containing sand and a little clay matter, the embank