_See also Glossary, or Explanation of Terms_, page 107. AN ELECTRICAL CENTRAL-STATION. As the term “central-station” associates itself with some pretentious building, such as a railway terminus, it may be advisable to remark that the similarity is only in the words, and that central-station is an abbreviation of central generating station, or building designed to contain the plant for the public supply of electricity. In the early days of electric lighting the transmission of electricity to a distance was considered an impossibility; we find the late Sir William Siemens, in his Presidential Address at the Society of Arts on the occasion of the opening of the session in 1882, stating “that a quarter of a mile in every direction from the lighting station was the area which would be as much as could be economically worked;” and, in order to tap the most paying district, it was proposed to establish a station in the most central spot. Sir William Siemens suggested the utilisation of the public squares, which could be excavated to a depth of twenty-five feet, and then arched over to the existing ground level, and in this covered space the engines, boilers, and dynamos were to be fixed; the only erection above the surface was the chimney, which was to be of ornamental design and combined with the ventilating arrangements of the subterranean chamber. The great inventor, who so ably filled the presidential chair at the meeting where these words were spoken, would be astonished to find that in London one electric lighting company has already erected seventy miles of overhead wire, and that customers are supplied miles away from the so-called central-station. The changed position of electricity is due to the introduction of the transformer by Goulard, who showed, at the Turin Exhibition of 1884, that a high-tension current could be transformed into a low-tension working current of safe potential, fifty miles away from the generator, in a successful and economical manner, and that the generating station might, therefore, be located outside the area to be lighted. In large cities this is a great advantage, the value of land often precluding the erection of a big station in the working area; for this reason small stations are often arranged in basements, under a large building, which are, as a rule, specially designed. This plan is somewhat similar to that adopted in the United States, where it is not unusual to find a successful installation in a basement and sub-basement, the general arrangement being of similar character to the engine-room of a steamship. A station is being erected in Philadelphia on a ground space of 72 feet × 100 feet, which is to supply 60,000 lights; the building is six-storied, the dynamos are on the first floor, the boilers on third, the coal stores on fourth, and the offices on the fifth.