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the earth. To prevent leakage, the bottoms of the canals are lined with concrete, while the side walls are of brick.

of the best in the world, and, in some respects, resembles that of Paris. Figs. 2 and 3 show typical scenes during the construction of these canals.

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Pumping to Higher Levels The waterways are divided into eight groups, each being served by a set of pumps operated by electric power.

In all, 26 pumps are in service, having a total discharging capacity of 7,600 cubic feet per second, with erage lift of 12 feet. They are connected by a system of wires with the generating station from which all of the power is secured. This building (Fig. 4) is 181 feet in length, 140 feet in width, and two stories high. An interior view is shown in Fig. 5. The building contains an equipment of 7 units, each consisting

FIG. 4. CENTRAL POWER STATION, WHERE POWER FOR

THE SEVERAL PUMPING STATIONS IS GENERATED.

Those which are constructed beneath the streets (Fig. 1) have roofs formed of steel framework, which in turn support

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FIG. 5. INTERIOR OF CENTRAL POWER STATION, NEW ORLEANS DRAINAGE SYSTEM.

One-half of engine room is here shown.

brick arches to uphold the roadway. Considering the difficult character of the work, the system is considered to be one

of a steam engine direct-connected to a generator, and each unit developing 2,000 horse-power. Steam is supplied

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FIG. 6. SUCTION BASIN AND PUMPING STATION NO. 7, PARTIALLY COMPLETED. horse-power. The boilers are of the tu ally located at the terminus of the princibular type, and are provided with chain- pal receiving canal in the locality, the grate mechanical stokers.

In addition water draining by gravity into a suction to the generating units and boilers, the basin (Fig. 6), from which it is forced station also contains two small steam by the pumps into a discharge basin (Fig. engines for auxiliary use.

7), thence passing through another chan

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FIG. 7. DISCHARGE BASIN AND PUMPING STATION NO. 7, PARTIALLY COMPLETED.

nel, to be pumped into the outlet canal

New Activity in Building and finally discharged into Lake Borgne, One of the results of the extraction a large inlet from the Gulf of Mexico, 12 of the moisture from this great "sponge miles east of the city.

upon which the city rests, is the activity

in building. Already the business secSewerage Below Water-Level

tion of New Orleans has undergone a Realizing the need of adequate sewers

remarkable transformation. Since the in connection with the drainage system, principal canals have been completed, it a portion of the fund which has been has been found possible, in these disprovided is being expended for this im tricts, to erect buildings of brick, stone, provement. Only a beginning has been and iron, which compare favorably with made; but about five miles of sewers those to be found in other large cities of have thus far been completed, and the country; and the area of one-story it is intended to have the prin- and two-story buildings appears to be cipal streets in the 560 miles of thor at an end. Contracts have recently been oughfare that traverse New Orleans, let for a hotel which will be twelve properly sewered within the next decade. stories high-a remarkable altitude for Contracts have already been let for an a New Orleans building. Although this extensive area. Provision has also been

Provision has also been building will contain several thousand made for an ample supply of pure water, tons of steel, the site upon which the so that the people in future will not have structure is to stand has become so firm to depend upon wells for their supply of that architects say it can be built with enthis necessary of life.

tire safety and with but little difficulty.

A Quarter-Century of
American Central Station Engineering

The Marvelously Rapid Progress in Electrical Engineering which has

Revolutionized Industrial Conditions

Part II.

By R. F, SCHUCHARDT, B, S.
Testing Laboratory, Chicago Edison Company

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Alternating-Current Systems

ried on by Shallenberger, Stanley, and O MUCH for the early develop- others, appeared in the plant installed at ment of the direct-current systems,

Buffalo, N. Y., in November, 1886. The of which the cities cited are char- following year, 65 plants, with a total ca

acteristic examples. Let us see pacity of 125.000 lights, were built; and when the alternating current entered the increase thereafter was rapid. the field. The development of the With a direct-current three-wire sysalternating-current system in America is tem using 230 volts between outside condue largely to Mr. George Westinghouse, ductors, it is uneconomical to transmit who, in 1885, had built at Pittsburg, Pa., current much farther than one and a-half an experimental plant to work out the miles, because of the prohibitively large system devised by Gaulard and Gibbs in amount of copper necessary to keep England. The first commercial result down the loss in the feeders. The reof the Westinghouse investigations, car sistance of a conductor varies with the

PRIMARY

2300

TRANSFORMER

SECONDARY

lo LAMPS

FIG. 14.

CONNECTIONS OF A. C. SYSTEM WITH

length; and as it requires the expenditure wound for use on 1,000-volt circuitsof energy to send a current over a re which was then considered as high as sistance, obviously a high resistance desirable, because of the difficulties of means a large amount of energy lost in insulating the line, the transformers, and the transmission. By increasing the other apparatus on which this voltage cross-section of the feeder, this resistance was applied. Rapid advance, however, can be kept low ; but the cost of the was made in the art of insulating, and feeder would then be prohibitive. By soon this primary pressure was doubled.

Most of the city A. C. distributing systems now have a primary pressure of about 2,300 volts. It is interesting to note that the insulators used on the early European high-tension lines were constructed with a trough along the edge on the inner side, which was filled with oil in order to prevent current leaking over the surface of the insulator to the pin and thus to ground, by way of the cross-arm and pole, on wet days.

One of the larger of the early stations for the generation and distribution of

alternating current was built in St. Louis, STATIC TRANSFORMERS.

Mo., in 1889. The system adopted was means of the alternating-current system single-phase, 1,200 volts, 60 cveles*, with static transformers, connected as with a three-wire Edison system for the shown in Fig. 14, energy can be trans secondaries. These secondaries were mitted at a much higher voltage from tied together at street crossings, forming the station. The higher the voltage of transmission, the smaller will be the current (amperes) for a given energy (watts): therefore, with the high-voltage system, a given energy can be transmitted over a much smaller wire than would be required for that same energy at a low voltage. In the transformers placed at or near the point where the current is to be used, the pressure is "stepped down" to the voltage of the lamps on the circuit.

The regulation—that is, the steadiness and constancy—of the voltage of these alternating-current lines, was very much poorer than that of the direct-current system. This was largely due to the effects of self-induction, which is ever present with alternating currents. The early incandescent lamp used on the direct Fig. 15. NETWORK OF Mains OF EDISON SYSTEM. current 110-volt systems was rather delicate, and had only a short life when burned on a circuit in which the pressure

Junction boxes, where mains connect with feeders. fluctuated very much. Consequently it a complete network similar to that decould not economically be used on the scribed for the direct-current system and existing alternating-current lines.

shown in Fig. 15. In this case the feedvolt lamp could be made far more stable, ers of the D. C. system were replaced by and, largely because of this, the second the high-tension A. C. feeders and transaries of the early transformers were

* A current which alternates 120 times per second has wound for 50 volts. The primaries were 60 double alternations or “cycles" per second.

SHOWING

MOTOR

Three-wire Feeders.
Three-wire Mains.

o

A 50

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