ELECTRICITY IN LONDON.

Timaru Herald, Volume LXXXIII, Issue 12910, 26 February 1906, Page 7

ELECTRICITY IN LONDON.

An engineer has written, the following racy account'of the electric power of the London District Railway : » i"ou probably know .that electricity has to be made. If you are interested so far, you might take a'walk one evening down the Lots road, in Chelsea. . You cannot fail to see the big power station, where they make the electricity for the London District Railway. I call it big, yet as buildings go it is not a very large one. Note the point, please. Vakness naturally appeals to you; but great power in small space is the word.in our trade, the word in all modem engineering.. Yet the Chelsea, building is' quite big enough to satisfy you. A matter of 6,170,000 bricks, 17,000 cubic feet.of terra, cotta, 50,000 superficial feet of glass, 8000 tons of steel and iron, 835 tons of cement, paint, and sundries, went to the making up of its mere shell, not counting what is inside -of it. Would you like to know what the machinery inside is like, how" it works, and what it requires to keep working? Every day of the year, including "Sundays, if the machinery is. asked to work at its maximum output of power, it must be fed mechanically—hand labour is here abolished -with 800 tons of the best steam coal, delivered to it from the Thames waterway by gantry electric travelling cranes, and stoked to it by mechanical chain-grate stokers. . (The old* hand stoker with whom you are acquainted, stripped to the waist, grimy to the eyes, all shovel and sweat! -is here a. thing of the past.) Everv hour of eveiy day it will call for 450 tons of water pumped from the earth. 575 feet below. Should the artesian well give out. pipes are laid on to the mains. Should both sources fail, pumps will bring water nj) from the Thames. . Yet a\ain, everv minute of every day this machinerv will demand 264 gallons of water-cooled* lubricating cil; for when the turbines are travelling at the rate of 1000 revolutions a minute (about 225 miles an hour) cool oil must continually run through their bearings. Steam—you know what steam is ?' It is the first consideration, .and it is made in 64 Babccck and Wilcox water-tube boilers each capable of turning 18,0001b of water every hour into steam. Each of these boilers has a heating surface of 5000 odd feet. From them the steam thev make is conveyed to the Westinghouse turbines vVhat is a turbine? In the old engine steam pushed winch- pushed a crank, which turned a smut, which turned a wheel. There was great kss cf power. In the turbine, the steam turns .the wheel at once direct c-umb:minr the results of all the old mechanism in a single action. It is so simple Liat a schoolboy can understand it It consists of a cast steel drum mounted on a shaft, and carrying rows of blades, the whole enclosed in a. stationarv cvlinder on the inner surface of which "are "s'imilar rings of fixed blades, alternating with the rows round the drum within. Into this cylinder,' and against, the opposing ring of blades, superheated steam is driven at hMi pressure. -, The blades on the drum. receiving the impulse from the steam, drive n- rcund. Simple to understand? Yet the whole srtorv.

In the Chelsea. power-house the drum of each turbine ean be driven ;t t the rate of 1000 revolutions per minute. Ef>ch turbine will yield 8000 horse- powe-. . -Si^ o :.- district trains, each with its full conYplement of carriages, carrying in all 10.0C0 passengers, took, sixteen of the old steam locomotives, one for each train, to tod' the lot of themV Now a single little machine does the work of the sixteen steam. locomotives It is .not as long as a single carriage. Part of it is the turbine, part the dynamo, which generates the electricity; hence it- is called a Westinghouse turoo-geuerator. The eight turbo-genera-tor? installed at Chelsea Lave therefore a capacity of 64,000 horse power, three or four times that- of the largest ocean liner's reciprocating engines. Electricity is made in this Westino-house dynamo coupled to tbe turbine, and "so the turbine has brought to birth a new type of dynamo of diminutive size and tremendous speed, which is gradually kiHirn- the gigantic machine formerly necessarv to accommodate the speed of'the slow-running piston engine. Economy in time and ee£ nomy in fuel are the result. The dvnamo coupled to the modern. West-inghouse tur-nii'-e is p.bout-one-eighth of the she cf the old machine. Like the turbine itself, the Chei.*ea dynamos can run at tlie rate of 1000 revolutions a minute, and- the will yield sufficient current to licrht U-eously abcut eight candle-

power electric lamps. If you wanted to light the sea-way from Southampton to New York with this current, you could hang a lamp about every five yards. And the way in which this electricity is made? You must take it as made. You would not be able to follow me if I talked about volts, kilowatts, amperes, ohms, and frequency. :

And how is.the electrical energy used? It is sent from Chelsea, through hightension cables, to the fifteen sub-stations belonging to the District Railway, and thence to the lines. When the routes are completed there will be something like 360 miles of cables under the streets, protected by Doulton earthenware, laid in concrete beds. These sub-stations, scattered over London from Sudbury to East Ham. from Hounslow to the Mansion House, receive the 11,000 volt current coming in, and convert and transform it—two very distinct operations!—into direct working current of 500 volts. The feeder cables then take it to the " live rail" (the rail on the near side of the track), whence it is picked up by the shoes carried by the cars, led from them to the motors, returning with diminished pressure after performing its work through-another shoe, to the rail running m the centre of the track, and finally back to the sub-station again. That is the mere ABC of it. I have jumped a lot to avoid confusing vou. Half the things I could explain to vou I have left undescribed; and I have carefully refrained from dragging in other systems, .there is the Metropolitan system, "for example, more perfectly equipped than the District, with a power house at Neasden quite as perfectly equipped as the Chelsea house. I could enlarge on the Metropohtan system for hours, because it is as nearly perfect/as any in existence. You didn't know, • perhaps, that it is one of the most elaborate installations in the world—that the network of underground lines controlled by the Metropolitan and District Companies is bv far the mo<t complex in the world. London is still ahead of the world in this respect, though she began rather late in the race and with a big handicap. As a London citizen vou ought to feel a little proud of it.