That these small dynamos are capable of driving heavy cars filled with passengers at the rate of many miles an hour seems incredible; but faith, “the evidence of things not seen,” must come into play.
The craving for mere size, however, will be amply gratified when the great power house at Chelsea, built to supply the Metropolitan, District, and other railways, is completed (vide Chapter V.).
But what on earth is a kilowatt, or a volt, an ohm, or an ampère?—expressions that are rapidly becoming as familiar as the word horse-power.
Well, “horse-power” was a term invented long ago by engineers, who blandly asked one to imagine that an ordinary horse was capable of lifting a weight of 33,000 lbs. (or some 14½ tons) one foot high per minute. Now, electricity is a very exact science. There is no mere theory about it; and a unit is a definite quantity of power, known in that science as a “kilowatt hour.” Thus, a kilowatt, or 1,000 watts, is the equivalent in measured work of 1⅓ horse-power, equal to the lifting of 44,000 lbs. per minute, or the doing of so many units of work, either electric lighting, heating, machinery driving, or traction.
VARIOUS FORMS OF ELECTRIC LOCOMOTION
Electricity as a locomotive force is being presented to the public in various forms. There is the ordinary railway, like the Underground, that, cleansing itself, amending its ways, and becoming converted to the new order of traction, has been granted a new lease of life. Then there are new lines laid down, intended from the first to be electrical, with specially designed cars, diving beneath the Thames, and connecting the north and south of London. These are our metropolitan pioneer electric railways. There is also the system of railways specifically and popularly known as Tubes, most important factors in the travelling world of modern Babylon. Another division is the system known as Overhead Electric Railways; that is to say, rails laid upon iron girders supported by columns above the roadway, a notable example of which is the Liverpool Overhead Electric Railway.
Electric tramways are with us in Greater London for good and all, with their network of lines in every direction. Some are locally worked by the various Borough Councils; others on a comprehensive scale by the London County Council, who now strongly advocate also another system, the Shallow-Underground, by which the cars run in a kind of open trench just below the surface in the middle of the street.
Next we have endless provincial and urban council electric tramways, including some very extensive systems for feeding the enormous traffic of cities and large towns in the Midlands and North of England.
Electric Light Railways, originally intended to be worked on rails laid down upon the ordinary highway, form a special class by themselves to serve short-distance traffic in country districts; but to all intents and purposes they are rural electric trams.
Lastly, we have motor-cars, carriages, omnibuses, cabs, vans, and cycles, that with electricity as their means of propulsion, will possibly ere long supersede every other form of traffic in our streets and along our roads and lanes.