Page images


[graphic][merged small]

AtsN interesting transporter 1890, other improvements were made, and

s bridge or aërial ferry has a subway scheme was also considered.

recently been constructed A transporter bridge was recently conat Newport in England, structed at Bilbao, Spain, and its great connecting the old town success caused it to be considered the

on the western bank of best solution of the difficulty. After inthe River Usk with the new town on the specting also the Rouen transporter, this eastern bank. This bridge is electrically type of electrically-driven aërial ferry reoperated, and, as shown in the accom- ceived parliamentary sanction in the year panying illustrations, is similar in con- 1900; and, two years later, tenders were struction to the electric aërial ferries at obtained for the work. Duluth, Minnesota, and at Rouen and The Newport bridge consists of a horMarseilles, France. It cost about one- izontal railway track supported by a third of a million dollars. Of this amount bridge spanning the river at such a the foundation piers and anchorages cost height as to allow the tallest ships using over $100,000; the steel superstructure the channel, to pass underneath without and traveling apparatus, about $150,000; striking their upper masts. The span is and the electrical equipment, motor 645 feet from center to center of the house, and shore abutments, as well as towers, and 592 feet between the faces the Eastern pier and lattice girder span, of the piers. The clear height to the unabout $30,000.

derside of the stiffening girder from About a century ago, these two old high-water mark, is 177 feet at ordinary English towns were connected by a five- spring tide ; and the height of the tower arch stone bridge. This was finally from the pier cap or level of the apwidened, and cantilever footpaths con proach road, to the saddle, is 241/2 feet. structed on both sides, in 1866. About It may be stated that the distance between the centers of anchorages is 1,545 motors. These motors are installed in feet, and the distance from the center of a steel-frame building placed over the the tower to the center of the anchorage approach road at the eastern end of the 450 feet.

bridge. Each has a capacity of 35 brake An electrically-operated car or travel- horse-power, series controllers being ing frame runs on the bridge, and is so utilized, worked from the pilot-house, for arranged that it can move freely in a the necessary electrical control. Insulongitudinal direction, its motion being lated conductors connecting this appararrested or reversed at will. This travel- atus are installed from the pilot-house to ing frame and service platform weighs the traveling frame, where they are con16.3 tons, while the suspension cables nected up to underrunning trolleys. A

third controller is provided, from which the bridge can be worked in case there is an accident to the overhead electrical equipment. The controllers are in duplicate in the pilot-house; and an automatic circuit-breaker and various other electrical instruments are also provided.

The maximum rate of travel of the service platform is ten feet per second ; and an elastic or movable buffer is provided at each river-wharf space of the fixed structure, in order to absorb the momentum of the car and prevent shock. There is a lattice girder span, as shown in the accompanying illustration, supported on a separate pier, connecting the car with the shore abutment at the eastern end of the bridge. The steel wire


of 63.5 tons.

This bridge has an easy stairway ex

tending from the ground to the platform SUSPENDED CAR CROSSING THE RIVER.

level on each tower; and the stability of

the tower against overturning is at a weigh 2.9 tons, and the car 31.5 tons, minimum when it is standing as an isomaking a total weight of 50.7 tons. The lated structure. It is stated that wind structure was designed for a load of 65 pressure of 56 pounds to the foot on the tons in addition to its own weight, and side facing the wind was allowed for in this platform or carrier is suspended the calculations, and one-half this from the traveling frame, being hung at amount on each of the leeward faces. the level of the bank of the river to be The electrical operation of the ferry is crossed.

said to be entirely satisfactory, thousands The car is lighted by electricity, and of passengers being carried daily, with is propelled by means of steel wire ropes large quantities of freight and many wound on a drum worked by two electric teams.

World's Largest Pump

By Dennis H. Stovall

[ocr errors]
[ocr errors]
[ocr errors]

a HE biggest high-pressure river. It requires 1,500 horse-power to

pump in the world is in- . operate the pump. Its central shaft, on stalled in the Dry Dig- which the five centrifugal turbines regings placer fields of volve, has a diameter of six inches, and southern Oregon, on weighs seven tons. The two main bear

Rogue river, and is used ings weigh a ton each. The system of oilto operate a battery of hydraulic mon ing is by a sight feed through glass cups. itors in the mines. This pump is one of The pump proper is made of one-inch the largest pieces of mining machinery pressed steel, and it is said that two niaever manufactured, and could never have chines were broken in manufacture in an

attempt to reach the maximum pressure was dumped directly from the cars to the of 250 pounds. The pump operates unfoundation prepared for it at the mines. der a normal pressure of 185 pounds to

The pump was built by the Byron the square inch. Both the speed and the Jackson Machine Works, of San Fran- pressure of the pump are registered by cisco, and was one of the last big jobs gauge, and are controlled by regulating done by this company before the earth- the power volume. quake and fire. The pump is of the five-step centrifugal type; and it weighs, aside from bearings and gears, just 70,000 pounds. Other

SS.CALIS 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

Largest High-PRESSURE PUMP. through a half-mile of pipe line, the pipe being of steel, 22 inches The mammoth pump is operated conin diameter. The water is lifted to a tinually, being shut down only twenty height of 100 feet, and forced through minutes each evening for an inspection two four-inch nozzles, hurling streams a of the bearings and gear. The serious distance of 500 feet. These powerful problem that confronted its operators streams are played upon the mountain was that of stopping and starting it, as walls, to tear down the gold-bearing every time it is closed down, it releases its gravel.

herculean force from behind 26,000 galPower to operate the pump is supplied tons of water, the volume required to fill by a power dam, built across Rogue the long pipe line. To prevent the grav- ity weight of this volume from hurling the water through a side pipe into the the water back upon the pump, a check race, and slowly closing it, thus switching valve is placed at the base of the pipe the pump to the main line by degrees, line. The work of starting the punip until it attains its normal working speed against this long and heavy column of and pressure. The pump satisfactorily water is made simple by first releasing does the work for which it was designed.


A Cape-to-Cairo Feeder

By J. Hartley Knight

ONSIDERABLE progress district supposed to be fabulously rich in

has lately been made on copper.
the Benguella railway, The line, which is the outcome of a
which commences at Lo- concession granted to a British capitalist,
bito Bay in Portuguese has already been laid for a distance of

West Africa and runs al- fifty miles; and, the initial engineering most due east across the continent to difficulties once overcome, the rest will Katanga—900 miles away-near Lake be comparatively easy, as the country Tanganyika in the Kongo territory, a beyond is almost as flat as a table. The

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




section of the great trunk line, are also the consultiig 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


In course of construction. then follows, for a short distance, the right side of the gorge, till a side, twenty feet above the river bed. break in the side of the hill forces it Further on, a steep gradient has necesagain to span the gorge, soon after which sitated the construction of a special rack it again returns, crossing in all three railway laid between the ordinary lines. bridges before it is once more out of the The second bridge is nearing completion, gorge. The first bridge is one of five and the third will be taken in hand at spans, with three spans on the curve and once, and pushed on to completion. It two tangent, with concrete piers and is anticipated that the work will be finabutments, which raise it, on the Lengue ished within three years.

[graphic][merged small][merged small]
« PreviousContinue »