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World's Largest Pump

By Dennis H. Stovall

HE biggest high-pressure pump in the world is installed in the Dry Diggings placer fields of southern Oregon, on Rogue river, and is used to operate a battery of hydraulic monitors in the mines. This pump is one of the largest pieces of mining machinery ever manufactured, and could never have been installed but for the fact that it was dumped directly from the cars to the foundation prepared for it at the mines.

The pump was built by the ByronJackson Machine Works, of San Francisco, and was one of the last big jobs done by this company before the earthquake and fire. The pump is of the five-step centrifugal type; and it weighs, aside from bearings and gears, just 70,000 pounds. Other pumps have been built that lift as great a volume of water as does this one, but they do not deliver it under such enormous pressure. This pump is tested to withstand a maximum pressure of 250 pounds to the square inch. Its capacity is 13,000,000 gallons per day of 24 hours, or 9,000 gallons per minute. This enormous volume is delivered through a half-mile of

pipe line, the pipe being of steel, 22 inches in diameter. The water is lifted to a height of 100 feet, and forced through two four-inch nozzles, hurling streams a distance of 500 feet. These powerful streams are played upon the mountain walls, to tear down the gold-bearing gravel.

Power to operate the pump is supplied by a power dam, built across Rogue

river. It requires 1,500 horse-power to operate the pump. Its central shaft, on which the five centrifugal turbines revolve, has a diameter of six inches, and weighs seven tons. The two main bearings weigh a ton each. The system of oiling is by a sight feed through glass cups. The pump proper is made of one-inch pressed steel, and it is said that two machines were broken in manufacture in an attempt to reach the maximum pressure of 250 pounds. The pump operates under a normal pressure of 185 pounds to the square inch. Both the speed and the pressure of the pump are registered by gauge, and are controlled by regulating the power volume.

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LARGEST HIGH-PRESSURE PUMP.

The mammoth pump is operated continually, being shut down only twenty minutes each evening, for an inspection. of the bearings and gear. The serious problem that confronted its operators was that of stopping and starting it, as every time it is closed down, it releases its herculean force from behind 26,000 gallons of water, the volume required to fill the long pipe line. To prevent the grav

ity weight of this volume from hurling the water back upon the pump, a check valve is placed at the base of the pipeline. The work of starting the pump against this long and heavy column of water is made simple by first releasing

the water through a side pipe into the race, and slowly closing it, thus switching the pump to the main line by degrees, until it attains its normal working speed and pressure. The pump satisfactorily does the work for which it was designed.

A Cape-to-Cairo Feeder

By J. Hartley Knight

CONSIDERABLE progress has lately been made on the Benguella railway, which commences at Lobito Bay in Portuguese West Africa and runs almost due east across the continent to Katanga 900 miles away-near Lake Tanganyika in the Kongo territory, a

district supposed to be fabulously rich in copper.

The line, which is the outcome of a concession granted to a British capitalist, has already been laid for a distance of fifty miles; and, the initial engineering difficulties once overcome, the rest will be comparatively easy, as the country beyond is almost as flat as a table. The

A CUTTING THROUGH GRANITE ON LENGUELLA RAILWAY.

contractors have to grade up 5,000 feet in 200 miles in hard granite country; and when the plateau is reached, it is anticipated that a mile a day in rail-laying will be easily covered. As it is, the work of construction is being pushed on very rapidly; and ultimately, there is very little doubt, the line will link up at Broken Hill in Rhodesia, the present rail-head of the line that is to connect Cape Town and Cairo. Sir Douglas Fox and his partners, and Sir Charles Metcalfe, who have engineered the Rhodesian

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section of the great trunk line, are also the consulting engineers of the Benguella railway.

For a considerable distance inland from Lobito Bay, a great amount of blasting in solid granite has had to be efected. At the time of writing, the rail-head is at the Lengue gorge, where some heavy bridge work will have to be constructed. Where the bed of the Lengue is joined by that of another river, it has been necessary to fling a bridge. over to the other side of the gorge; and the line then follows, for a short

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Tests of Water Wheels

By Paul Arr

TUDYING the action of water on water wheels at a recent special demonstration in San Francisco, has resulted in modifying several long-established hydraulic theories. It is .shown that most of these supposed hydraulic laws were mere empiricisms reduced from observations of water action against stationary surfaces; or, if moving, the path of the water was so obscured by spray and the moving wheel that the observations led to mistaken theories, which were disproved by actual demonstration.

The demonstrations which were made with Pelton water wheels showed that the correct method of solving the problems was to observe the action of water on moving surfaces as though they were standing quite still. This is accomplished by applying the stroboscopic

FIG. 1. À 4,000-H. P. TANGENTIAL WATER WHEEL.

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if a moving object be illuminated at fixed intervals by rays of light admitted at the moment the object passes a desired position, each portion of the object will be observed as though it were stationary. Thus is secured a clear view of what occurs in the cups or buckets of the water wheel while it is in operation under normal conditions.

As an exponent of this principle, there was exhibited the apparatus shown in Fig. 3, consisting of a wheel 20 inches in diameter, mounted on the shaft overhang of a General Electric generator. The water impinges on the wheel through a needle nozzle, the pressure being supplied by a centrifugal pump. The luminant is a General Electric searchlight projector with automatic focal-point control, which is located beneath the apparatus, and which, by a system of mirrors, . throws its rays into the wheel housing through the glass bottom. In its normal position the light is thrown directly on the wheel, which may be seen revolving and the water discharging from the buck

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FIG. 3. GENERAL VIEW OF STROBOSCOPIC APPARATUS.

splendid results; but the fallacy lay in the fact that most of the hydraulic laws were deduced from observations of water action against stationary surfaces.

The recent tests thoroughly demonstrated that one of the fundamental principles of hydraulics, as applied to impulse wheels, is that the water must "enter without shock and leave without velocity." The nearer the approach to this condition, the higher the resultant efficiency. Experiments with the buckets showed that in order to obtain a complete reversal of the stream, with practical absence of velocity, it is essential that the bucket be divided into two parts by a wedge or splitter on which the stream may strike (Fig. 1). In the recent demonstrations, the stream of water was thus divided, the two halves following the curvature of the bucket and discharging backward and downward at a slight angle.

The unique method of observation here described, demonstrated that an impulse water wheel, in order to attain the highest bucket efficiency, must meet the following conditions:

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1. The front wheel of the bucket, in entering the stream of water, should produce abso

2. The water velocity should be taken up on the surface of the bucket in a line vertically under the shaft center, when the bucket surface is in the most advantageous position.

ets in apparent confusion. Interposed
between the searchlight and the wheel is
a sheet-iron disc with radial slots, which
is revolved by means of gearing at a
speed proportional to that of the wheel;
and when the searchlight is automatically lutely no disturbance.
brought into its upper position, the light
is thrown on the wheel through these re-
volving slots. The wheel is thus illumi-
nated at fixed intervals, as explained pre-
viously; and the onlooker sees it appar-
ently standing still, and can observe the
action of the water, as well
as trace the path of the jet,
from its entering the bucket
to its reversal and clearance
of the succeeding buckets.

In designing the waterwheel bucket and attempting to carry out a particular theory, it is necessary to lay out the bucket shape mathematically, and then, following established hydraulic laws regarding the flow of water on surfaces, note the curves and paths which the stream should follow. This plan the only one heretofore known-has been productive of some

3. The water should discharge from the sides of the buckets without interference with the succeeding buckets or the wheel center, and with a minimum velocity of discharge.

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FIG. 5. STREAM OF WATER FROM NEEDLE NOZZLE,

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