135 THIRD PERIOD-THE PRACTICAL. SYSTEMS IN ACTUAL USE. "The invention all admired; and each how he To be the inventor missed-so easy seemed Once found, which yet unfound most would have thought SIR W. H. PREECE'S METHOD. SIR WM. PREECE, lately the distinguished engineer-in-chief of our postal telegraphs, has made the subject of wireless telegraphy a special study for many years, his first experiment dating back to 1882.1 From that year up to the present he has experimented largely in all parts of the country, and has given us the results in numerous papers-so numerous, in fact, that they offer a veritable embarras des richesses to the historian. In what follows I can only attempt a résumé, and that a condensed one; but to the reader greatly interested in the subject I would advise a careful study of all the papers, a list of which I append :— 1. Recent Progress in Telephony: British Association Report, 1882. 1 Indeed, it so happens that one of the first experiments he ever made in electricity was on this very subject in 1854. See p. 28, supra. 2. On Electric Induction between Wires and Wires: British Association Report, 1886. 3. On Induction between Wires and Wires: British Association Report, 1887. 4. On the Transmission of Electric Signals through Space: Chicago Electrical Congress, 1893. 5. Electric Signalling without Wires: Journal of the Society of Arts, February 23, 1894. 6. Signalling through Space: British Association Report, 1894. 7. Telegraphy without Wires: Toynbee Hall, December 12, 1896. 8. Signalling through Space without Wires: Royal Institution, June 4, 1897. 9. Etheric Telegraphy: Institution of Electrical Engineers, December 22, 1898. 10. Etheric Telegraphy: Society of Arts, May 3, 1899.1 In his first-quoted paper of 1882, speaking of disturbances on telephone lines, Sir William says: "The discovery of the telephone has made us acquainted with many strange phenomena. It has enabled us, amongst other things, to establish beyond a doubt the fact that electric currents actually traverse the earth's crust. The theory that the earth acts as a great reservoir for electricity may be placed in the physicist's waste-paper basket, with phlogiston, the materiality of light, and other old-time hypotheses. Telephones have been fixed upon a wire passing from the ground floor to the top of a large building (the gas-pipes being used in place of a return wire), and Morse signals, sent from a telegraph office 250 yards distant, have been distinctly read. There are several cases on record of telephone circuits miles away from any telegraph wires, but in a line with the earth terminals, picking up telegraphic signals; and when an electric-light system uses the earth, it is stoppage to all 1 This list does not pretend to be complete. Doubtless there are other papers, which have escaped my notice, telephonic communication in its neighbourhood. Thus, communication on the Manchester telephones was not long ago broken down from this cause; while in London the effect was at one time so strong as not only to destroy all correspondence, but to ring the telephone - call bells. A telephone system, using the earth in place of return wires, acts, in fact, as a shunt to the earth, picking up the currents that are passing in proportion to the relative resistances of the earth and the wire."1 He then describes the experiment which he had recently (March 1882) made of telegraphing across the Solent, from Southampton to Newport in the Isle of Wight, without connecting wires. "The Isle of Wight," he says, "is a busy and important place, and the cable across at Hurst Castle is of consequence. For some cause the cable broke down, and it became of great importance to know if by any means we could communicate across, so I thought it a timely opportunity to test the ideas that had been promulgated by Prof. Trowbridge. I put a plate of copper, about 6 feet square, in the sea at the end of the pier at Ryde (fig. 17). A wire (overhead) passed from there to Newport, and thence to the sea at Sconce Point, where I placed another copper plate. Opposite, at Hurst Castle, was a similar plate, connected with a wire which ran through Southampton to Portsmouth, and terminated in another plate in the sea at Southsea Pier. We have here a complete circuit, if we include the water, starting from Southampton to Southsea Pier, 28 miles; across the sea, 6 miles; Ryde through Newport to Sconce Point, 20 miles; across the water again, 1 mile; and Hurst Castle back to Southampton, 24 miles. "We first connected Gower-Bell loud-speaking telephones in the circuit, but we found conversation was impossible. Then we tried, at Southampton and Newport, what are 1 For early notices of the same kind, see pp. 74-80, supra. called buzzers (Theiler's Sounders)-little instruments that make and break the current very rapidly with a buzzing sound, and for every vibration send a current into the circuit. With a buzzer, a Morse key, and 30 Leclanché cells at Southampton, it was quite possible to hear the Morse signals in a telephone at Newport, and vice versa. Next day the cable was repaired, so that further experiment was unnecessary." » 1 Preece, however, kept the subject in view, and in 1884 he began a systematic investigation, theoretically and experi 1 Captain (now Colonel) Hippisley, R. E., who conducted these trials, thought that the presence of the broken cable across the Solent somewhat vitiated the results, as its heavy iron sheathing may have aided in conducting the current. mentally, of the laws and principles involved-an investigation which he has hardly yet completed. In his papers read at the International Electrical Congress, Chicago, August 23, 1893, and at the Society of Arts, London, February 23, 1894, he gives a résumé of his experiments from 1884 to date. He begins the latter paper by asking the same momentous question which a lady once put to Faraday, What is electricity? Faraday, with true philosophic caution, replied (I quote from memory): "Had you asked me forty years ago, I think I would have answered the question; but now, the more I know about electricity, the less prepared am I to tell you what it is." Sir William is not quite so epigrammatic, nor nearly so cautious; but, then, we have learned a great deal since Faraday's time. "Few," he says, "venture to reply boldly to this question—first, because they do not know; secondly, because they do not agree with their neighbours, even if they think they know; thirdly, because their neighbours do not agree among themselves, even as to what to apply the term.1 The physicist applies it to one thing, the engineer to another. The former regards his electricity as a form of ether, the latter as a form of energy. I cannot grasp the concept of the physicist, but electricity as a form of energy is to me a concrete fact. The electricity of the engineer is something that is generated and supplied, transformed and utilised, economised and wasted, meted out and paid for. It produces motion of matter, heat, light, chemical decomposition, and sound; while these effects are reversible, and sound, chemical decomposition, light, heat, and motion. reproduce those effects which are called electricity." 1 "Substantialists" call it a kind of matter. Others view it as a form of energy. Others, again, reject both these views. Prof. Lodge considers it a form. or rather a mode of manifestation, of the |