Page:Popular Science Monthly Volume 34.djvu/431

Rh states that the telegraph business which, when assumed by the Government in 1870, brought in £550,000 per annum, now yields £2,000,000 per annum; and that the annual number of messages has increased from 6,000,000 to 52,000,000. What the increase in revenue and work done would have been had the telegraphs remained in private hands, it is impossible to say. Government telegraphing is cheap—6d. for a message to any part of the United Kingdom—and that, no doubt, tends to make it popular. Mr. Preece refers with natural pride to the leading part Great Britain has taken in the laying of submarine cables. British ships, he states, have laid 110,000 miles of cable; and British capital to the amount of £40,000,000 has been expended in this very useful work. The railway system of to-day could not have reached its present development without the aid of the telegraph, by means of which the whole movement of trains is checked and controlled from moment to moment. A well-equipped signal-box on a main line of railway is a very interesting place to visit. To quote the words of the address: "The signal-man is able to survey the lines all round him by the aid of his electric signals; he can talk by telegraph or telephone to his neighbors and his station-master; he learns of the motion of the trains he is marshaling by the different sounds of electric bells; he controls his out-door signals by the deflection of needles or the movement of miniature semaphores; he learns the true working of his distant signals by their electric repetition; machinery governs and locks every motion that he makes, so that he can not make a mistake." The safety thus secured for the traveling public is indicated by the fact that in the whole United Kingdom the average annual loss of life by railway accidents in the five years ending 1887 was only sixteen, or, as Mr. Preece computes it, one life to every 35,000,000 journeys made by train.

Great inventions have often a considerable period of incubation before they assume their proper importance and development. Thus, nearly seventy years elapsed between the discovery of the electric light by Sir Humphry Davy and its practical introduction for purposes of street-lighting. Mr. Preece is enthusiastic for the electric light, which he contrasts in its purity and wholesomeness with "filthy gas and stinking oil." He states that in the Central Savings-Bank, at London, the introduction of the electric light was followed by an appreciable improvement in the health of the staff. Every year sees some increase of efficiency or diminution of cost in connection with this admirable system of lighting. At this moment it is beyond comparison the cheapest method of producing any given unit of light. For the working of tram-cars or street-railways, Mr. Preece is of opinion that electricity is incontestably the agency destined to be most extensively used in the near future. In saying this he has in view the climatic conditions of the British Isles; but there is good reason to expect that experiments now being made in this country will demonstrate that, even where snow-storms have to be contended with, electricity will carry the day in the contest with horse-flesh. The progress made in the electrolytic extraction of metals from their ores is shown in the fact that whereas not long ago it was considered economical to absorb 0·85 horse-power in depositing one pound of copper per hour, the same work can now be done with 0·3 horse-power. The uses, however, of electricity are almost beyond enumeration. We have electric welding, electric production of chlorine, iodine, and oxygen, electric decomposition of poisonous gases, electric fire-alarms and frost-alarms, electric photography, electric bells, electric clocks, electricity as a curative agent, and electricity as a substitute for hanging. The question as to what electricity is, or how it may be most correctly defined, will