This revolves on a 15-inch iron axle, reduced at the bearings to 12 inches, and is turned by a couple of cogged pinions, each 4 feet in diameter, mounted on a 12-inch crank shaft. These pinions gear into the cogged bands on the outer edges of the wheel. The shaft bearing the cogged pinions is connected directly, through cranks, with two large low-pressure condensing beam engines. These engines have each 7-foot stroke and 36-inch cylinders, and are each capable of developing 175 horsepower, or a total of 350, on a consumption of 900 pounds of coal per hour. The central portion of the wheel, 8 feet in width on the face between the cogged bands, is divided into twelve openings, each about 18 inches wide at the mouth, and these are the entrances to spirally curved buckets of the full width of the wheel, which enlarge as they approach the center and then diminish at their inner or discharge orifices to a width of 2 feet. Surrounding the main axle is a conical wooden hub, from 8 to 11 feet in diameter, so designed that the water falling on it from the buckets is thrown in either direction and empties into two canals, one leading away from each side of the wheel, discharging a little beyond into the main canal. The buckets terminate within 4 feet of this central hub, and have an inside depth along the diameter of the wheel of 12 feet. As the wheel revolves, the buckets fill by immersion in the feeder canal, and the water falls out at the lower end of these buckets onto the hub and thence into the out-take canals. The lift from the surface of the feeder canal to the surface of the out-take canal is 14 feet. The wheel makes 100 revolutions per hour, and is capable of lifting 300,000 cubic feet of water per hour to this height. This is equivalent to about 170 acre-feet of water per day of twenty-four hours, or about 83 second-feet flowing continuously. This, on a consumption of about 10 tons of coal for twenty-four hours at $5 per ton, or $50, is equivalent for fuel alone to a charge of about $1.30 per acre-foot. The efficiency of this machine seems to be relatively so high as a pumping machine for low lifts and large volumes that it is not improbable that it may be found advantageous to employ some such apparatus in irrigation.

Hydraulic rams may be utilized where there is a trifling fall and but a small amount of water is to be lifted. They work on the principle of a large volume of water having a small fall forcing by impulse blows a smaller volume to a higher elevation. Water is delivered to the ram from a reservoir or stream with steady flow through the supply or drive pipe. At the end of this is a check valve, opening into a chamber connected with the discharge pipe. As the water passes through the drive pipe it flows, with a velocity due to its height of fall, through a weighted pulse or clack valve which opens inward. It almost instantly closes this valve, and at the moment the issue of water ceases a ramming stroke is created which opens the delivery valve and permits the water to enter the air vessel, and at the same time, because of its velocity, the water flows back through the drive pipe. At the instant the backward flow begins the delivery valve closes and the pulse valve opens

to allow the passage of the water from the supply pipe, and the operation is repeated. In general, it may be stated that a hydraulic ram will elevate one-seventh of the supply volume of water to a height five times the fall, or one-fourteenth part to ten times the height of fall. The fall should range from 2 to 10 feet, but not more. Hydraulic rams are very cheap, both to purchase and to maintain, and are unaffected by tail water, as they will continue working even when flooded. It may be stated that in placing a hydraulic ram the length of drive pipe should be increased as the height to which water is lifted is increased, so that water shall not be forced back in the drive pipe as the pulse valve closes. The length of the drive pipe should in general be five to ten times the height of fall. The delivery pipe is usually from one-third to one-fourth the area of the drive pipe.

Of the many types of hydraulic rams in the market but few are of

sufficient capacity to perform the amount of work required in supplying irrigation water. Those which are capable of performing this work partake chiefly of the nature of hydraulic ramming engines, and are constructed somewhat differently from rams proper. They may be actuated by dirty as well as clear water, but are more intricate in their construction than are simple rams. One of the most effective of these engines is the Rife hydraulic ramming engine (fig. 16). This is said to be capable of elevating water to a height of 25 feet for every foot of fall, and to deliver one-third of the water used in operation to two and one-half times the height of fall, or one-sixth of the water to five times the height of fall. Only the largest of these are capable of elevating enough water for irrigation. Those having a drive pipe 8 inches and a

delivery pipe 4 inches in diameter are capable under a head of 10 feet of elevating about one-half of an acre foot per day of twenty-four hours to a height of 25 feet. Such a machine costs $500, or at the rate of about $10 per acre irrigated.

HOT-AIR AND GASOLINE PUMPING ENGINES.

These machines have been extensively used in the East for pumping moderate quantities of water for domestic consumption and for small factories or villages. Lately they have been successfully employed in pumping small irrigation supplies in the West, and are undoubtedly destined soon to gain popular favor, chiefly because of their simplicity, economy, and the ease with which they can be stopped and started and maintained in successful operation by unskilled labor. Hot-air pumping engines do not depend for their operation on power developed by the expansion of steam to convert heat into motion. Gasoline engines are likewise operated without converting the heat into steam, but by the expansive force produced by the explosion of vaporized gasoline when ignited in contact with air. Both of these types of engines are made only to develop comparatively small powers, and therefore are utilized in pumping but comparatively small volumes of water, usually irrigating from 5 to 50 acres. These engines have decided advantages over water and steam motors in that they can be employed where there is not sufficient water supply to operate a water motor and because of the kind of fuel which they consume, gasoline engines being serviceable in arid regions where fuel is expensive and difficult to obtain, and hot-air engines being capable of utilizing almost any variety of fuel. Moreover, these engines are small and compact, simple of erection by comparatively unskilled labor, and may be operated with the minimum expense for supervision and with little skill on the part of the operator.

Hot-air engines are constructed almost wholly for pumping purposes, the motive power and pumping apparatus being combined in one machine inseparably connected in one frame. They are so simple in operation that anyone capable of lighting a match may run them. There is no possibility of explosion, and when once started they require no further attention than for replenishment of fuel. They are made in capacities ranging from a few gallons per minute to one-tenth of a second-foot, equivalent to two-tenths of an acre-foot per day of twentyfour hours, limited by the height of lift, which varies from a few feet to 500 feet. The chief objection to hot-air pumping engines is their great first cost, which for the larger size is $600, or $6,000 per second-foot, equivalent to about $100 per acre irrigated.

Gasoline engines are used extensively in some portions of the West, notably in Kansas, for pumping water for irrigation. They are made of varicus dimensions, up to those capable of developing 50 horsepower and pumping a correspondingly large volume of water, and they are

constructed as combined motive and pumping plants or as separate motors to be attached to varying forms of pumps. The chief advantages which these machines have over other motive powers for pumping are their compactness and simplicity of installation and operation, and, above all, their cheapness, not so much for first cost as for ultimate maintenance, though in this latter item they do not surpass hot-air pumping engines. The largest of these engines are capable of elevating for low lifts as much as 3 second-feet of water, or 6 acre-feet per day of twenty-four hours, and lesser quantities to greater heights in proportion. The cost of operation of such a machine as this has been asserted to be for gasoline as low as $1.25 per day, or 20 cents per acre-foot. It is stated that these engines will pump water at a cost of about 1 cent per hour; and working ten hours a day, the largest size will elevate sufficient water to a height of 20 feet to irrigate about 320 acres if storage be provided. The first cost of the plant is from $400 to $600 for engines capable of irrigating 10 to 20 acres, and larger plants in proportion. This is at the rate of about $30 per acre without storage, and the cost of operation is about $1.25 per acre irrigated.

STEAM PUMPING ENGINES.

Of the many forms of motors utilizing steam power, the following two classes cover most of those which are of interest to irrigators: (1) those which utilize steam power by indirect transmission to the pump through gearing, belting, or other separable connection; (2) those which utilize steam power through an engine directly coupled with the pump, as direct-acting or fly-wheel pumping engines. It is not desirable to refer here to the many forms of steam engines and boilers employed in developing steam power for actuating plunger, centrifugal, or other pumps. They are innumerable and are manufactured in all varieties, forms, and sizes and at all prices. The irrigator must determine by consultation with makers of steam engines and boilers those which are best suited to the work which he has to perform. On the other hand, direct-acting engines, being inseparable from their pumps, may be here considered, as each differs not only in its motive power but in its pumping mechanism.

In endeavoring to determine the power required of a pump that it may elevate a given volume of water to a given height the same considerations must be dealt with as in transforming power developed by windmills or water motors into volumes lifted to given heights. This may be roughly stated by the formula: horsepower required, H. P., equals time of work in minutes, t, multiplied by volume of water in cubic feet, r, multiplied by weight of a cubic foot of water (623 pounds), w, divided by 33,000 pounds, the result to be multiplied by the height to which the water is elevated in feet, h, plus the resistance due to friction in pipes, f.

H. P. =

62t v 33,000

xh + f

The frictional resistance to flow is an indefinite quantity which may

be most easily determined by reference to such tables as Trautwine's or others giving fractional resistance for pipes of given diameters and lengths.

Direct-acting steam pumping engines differ from other steam pumps in that the motor and pump are combined inseparably in one mechanism, the power which performs work being derived from an ordinary steam boiler, not through an engine separately geared or belted to the pump, but directly from pump plungers which form part of the steam piston or connecting rod. Such direct-acting pumping engines may be either single or double acting. They have the water and steam euds centered in one line, so that the water plunger and steam piston are attached to the same piston rod and work together without an intervening crank or other connection. This is the simplest and most compact form of steam pumping apparatus, and is more extensively used for pumping than all other varieties of pumping machinery combined, though it is, perhaps, one of the most wasteful and expensive forms of steam engines. It is undoubtedly the most substantial and satisfactory form of steam pumping apparatus for lifts exceeding 20 feet, for it is less liable to derangement or accident and better fitted to perform constant, hard work than any of the separable steam engines and pumps. Machines of this class are manufactured by many establishments, and the qualities and efficiencies of the various makes are well established by competition and experiment. Steam pumping engines are similar in nearly all the various makes, differing chiefly in details of valve motion. Among the best of these are the Knowles, Blake, SmithVaile, Dean, Cameron, Worthington, and Davidson valve movements. In selecting steam pumping engines, among the points most desirable are strength and simplicity of working parts, large water valve area, long stroke and ample wearing surfaces, continuity of flow, simplicity of adjustment and repair, and moderate steam consumption. In choosing from the various makes of pumping engines it is well in corresponding with their makers to inform them, among other points, of the purposes for which they are to be used, height of lift and height to which water is to be forced, quantity of water to be elevated, motive power, and quality of fluid, as clear or muddy.

Direct-acting steam pumping engines may be either high-pressure or compound. The latter are economical in both fuel and water consumption, and their cost for operation is correspondingly less, though their first cost is a little greater. The best form of direct-acting are the duplex pumping engines, consisting of two direct-acting steam pumping engines of equal dimensions, side by side on the same bed-plate, with a valve motion so designed that the movement of the steam piston of one pump shall control the movement of the slide valve of its opposite pump so as to allow one piston to proceed to the end of the stroke and come to rest while the other piston moves forward on its stroke. All single-acting pumps should be provided with air chambers.