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Rh : J. Poole, The Practical Telephone Handbook; K. B. Miller, American Telephone Practice; W. Aitken, Manual of the Telephone; J. E. Kingsbury, Telephone and Telephone Exchanges. : Smith & Campbell, ''Auto. Telephony; R. Mordin, Strowger Auto.'' Telephone; Professional Papers of the Institution of Post Office Electrical Engineers: J. Hedley, ''W. E. Co.'s Semi-Auto. System''; B. O. Anson, ''W. E. Co.'s Auto. System''; Papers from the Journal of the Institution of Post Office Electrical Engineers: H. W. D., “Dudley Auto. Tp. Exch.” (Jan. 17); G. F. O., “Theoretical Principles of Traffic Capacity of Auto. Switches” (Oct. 20); W. J. Bailey, “Lorimer Exch. at Hereford” (July 13); W. J. Bailey, “Epsom Auto. Exch.” (vol. 5, 1912); J. Hedley, “Auto. Exch. Darlington” (vol. 7, 1914); R. L. Bell, “Auto. Switches in Split Order Wire Wkg.” (vol. 7, 1914); P. V. Christensen, “No. of Selectors in Auto. Tp. Systems” (vol. 7, 1914); “Coin Box and Call Meter for Auto. Exchanges” (vol. 8, 1915); J. Hedley, “Developments in the Strowger Auto. System” (vol. 8, 1915); A. K. Erlang, “Solution of Problems in Theory of Probabilities, Auto. Exchs.” (vol. 10, 1917); F. McMorrough, “Grimsby Exch.” (vol. 9, 1916); A. B. Eason, “Relay Auto. Tp. System” (vol. 13, April 20 1920); G. F. O., “Comparisons of Auto. Exch. Systems” (vol. 12, 1919); ''Proc. American I. E. E.'': W. Lee Campbell, “Traffic Studies in Auto. Switchboard Telephone Systems” (March 1914). Electric Currents in Telegraph and Telephone Conductors; J. G. Hill, Telephonic Transmission; Gherardi & Jewett, “Telephone Repeaters” (Journal of the American Institute of Electrical Engineers, Oct. 1919); B. Cohen & J. G. Hill, “Long Distance and Cable Telephony” (Journal of the Institute of Post Office Electrical Engineers, 1916); H. W. Malcolm, The Theory of the Submarine Telegraph and Telephone Cable; A. E. Kennelly, The Application of Hyperbolic Functions to Electrical Engineering Problems; Professional Papers of the Institution of Post Office Electrical Engineers: A. W. Martin, The Loading of Telephone Cable Circuits; A. G. Lee, Telephone Transmission; C. E. Hay, Alternating Current Measurements; J. G. Hill, The Loading of Aerial Lines; B. S. Cohen, Telephonometry; A. B. Hart, Telephonic Repeaters; C. Robinson & R. M. Chamney, Telephone Relays.
 * Prof. J. A. Fleming, The Propagation of

Arnold, H. D., and Crandall, I. B., “The Thermophone as a Precision Source of Sound,” Physical Review (v. 10, July 1917); Blackwell, O. B., and Colpitts, E. H., “Carrier Current Telephony and Telegraphy” (A. I. E. E. Journ., April, May and June 1921); Campbell, G. A., “Mutual Inductances of Circuits Composed of Straight Wires,” Physical Review (v. 5, June 1915); Carson, J. R., “On a General Expansion Theorem for the Transient Oscillations of a Connected System,” ibid. (v. 10, Sept. 1917); id., “Theory and Calculation of Variable Electrical Systems,” ibid. (v. 17, Feb. 1921); id., “Propagation of Periodic Currents over Non-Uniform Lines” (Electrician, March 4 1921); id., “Wave Propagation over Parallel Wires: the Proximity Effect” (Phil. Mag., April 1921); Carson, J. R. and Northrup, E. F., “The Skin Effect and Alternating Current Resistance” (Franklin Inst. Jour., Feb. 1914); Carty, J. J., “The Telephone Art,” ibid., July, 1916; Colpitts, E. H., and Craft, E. B., “Radio Telephony” ''Trans. Am. Inst. Elec. Eng.'' (p. 305, 1919); Fondiller, W., and Martin, W. H., “Hysteresis Effects with Varying Superposed Magnetizing Forces” (A. I. E. E. Jour., Feb. 1921); Fry, T. C., “Thermionic Current Between Parallel Plane Electrodes; Velocities of Emission Distributed According to Maxwell's Law,” Physical Review (v. 17, April 1921); id., “The Solution of Circuit Problems,” ibid. (v. 14, Aug. 1919); Gherardi, B., “The Commercial Loading of Telephone Circuits in the Bell System,” ''Trans. Am. Inst. Elec. Eng. (p. 1743, 1911); id.'', “Joseph Henry's Experiments in the Albany Academy, 1827-32, Interpreted in the Light of the Present Day” (13th Report of the Director of New York State Museum, 1916); Gherardi, B., and Jewett, F. B., “Telephone Repeaters,” ''Trans. Am. Inst. Elec. Eng. (p. 1287, 1919); id.'', “Progress in the Art of Communication” (Electrical World, Jan. 24 1920); Heising, R. A., “The Audion Oscillator,” Physical Review (v. 16, Sept. 1920); id., “The Audion Oscillator” (A. I. E. E. Jour., April and May 1920); Jewett, F. B., “Industrial Research with Some Notes Concerning its Scope in the Bell Telephone System,” Trans. ''Am. Inst. Elec. Eng.'' (p. 841, 1917); Kennelly, A. E., Laws, F. A., and Pierce, P. H., “Experimental Researches on Skin Effect in Conductors,” ibid. (p. 1953, 1915); Mills, J., “A General Method for Periodic Currents” (Soc. Prom. Eng. Educ. Bull., v. 8, 1918); Nichols, H. W., “Theory of Variable Dynamical-Electrical Systems,” Physical Review (v. 10, Aug. 1917); id., “The Audion as a Circuit Element,” ibid. (v. 13, June 1919); Osborne, H. S., “The Design of Transpositions for Parallel Power and Telephone Circuits,” ''Trans. Am. Inst. Elec. Eng.'' (p. 897, 1918); Rhodes, F. L., “The Wiring of Large Buildings for Telephone Service,” ibid. (p. 1367, 1912); Slaughter, N. H., “The Production of Vacuum Tubes for Military Purposes,” Physical Review (v. 14, Nov. 1919); Van der Bijl, H. J., “Electron Relays as Amplifiers and Oscillators” (Pop. Sci. Monthly, April, May and June 1920); Warren, H. S., “Inductive Effects of Alternating Current Railroads on Communication Circuits,” ''Trans. Am. Inst. Elec. Eng.'' (p. 503, 1918); Watson, T. A., “How Bell Invented the Telephone,” ibid. (p. 1011, 1915); Wente,

E. C., “A Condenser Transmitter as a Uniformly Sensitive Instrument for the Absolute Measurement of Sound Intensity,” Physical Review (v. 10, July 1917).  TELPHERAGE (see ). The World War saw, in the Italian army, amazing use made of the system of telpher transport for fighting on the Alps. When, after many years, snow, ice and avalanches will have all but cancelled every trace of the epic deeds performed in those regions, tourists who climb to the crests of the Adamello, the Marmolata, the Tofana and a hundred other peaks will hardly believe that thousands of men lived and fought for years in the very spots that they have reached only with difficulty, with the help of ropes and ice-axes, and in favourable weather.

Before the war it was thought impossible to conduct military operations on the high peaks. It was believed that the ordinary troops would be practically tied to the roads, that a company of “Alpini” with a few mountain guns would be the largest unit that could be used in places where only paths for mules existed, and that the rocky peaks, the snows and the ice, would be reached only by small groups belonging to specialist units, sent there to keep an eye on the enemy.

But from the earliest days of the campaign there happened on the Alpine front something very similar to what had occurred in France after the battle of the Marne, when Germans and French, in their common desire to outflank each other in the direction of the sea, finally reached the sea itself, thus forming one uninterrupted line from the Vosges to the Channel. On the Alps, with the object of capturing or turning the Austrian defensive lines, the Italians climbed higher and higher in ever-increasing numbers, the Austrians doing likewise, until the very tops of the mountains were reached and it became impossible to go farther. The most elevated points of the frontier having been thus occupied, the Italians put themselves in a position to meet enemy attacks as well as to face the inclemency of the climate: a hard and relentless struggle which had to be started afresh every time war operations involved a change of positions.

The first days of the war saw whole companies clinging hand and foot to the rocky summits; battalions encamped and freezing at a height of 3,000 metres. Field guns, drills, photo-electric stations were taken to pieces and carried up bit by bit to giddy heights, and there put together again. Food, water, ammunition were carried for many hours on mules, and thence transferred to columns of men who carried them for long hours more. At times the wounded and the sick had to be removed by securing them with ropes and letting them slide down gullies, or by allowing them to be jolted on stretchers along impossible paths. Very often they had to be attended to on the spot, behind a rock, because their condition did not allow of so painful a transport.

Numberless were the cases of men who, barefooted, with daggers in their mouths, would climb up the most impracticable summits during dark and stormy nights, and surprise the enemy where the latter felt sure that the ravines and precipices which surrounded him were his surest guards. Many times whole supply columns were crushed and buried by avalanches and rocks. Avalanches claimed thousands of victims among the troops on march, in hutments or in trenches. In certain places and at certain periods the danger was so great that when the men went out they were supplied with a long thin rope coloured in red. The colour came off with the damp and stained the snow, thus facilitating the search for men buried underneath.

The colossal work done at such great heights originated unheard-of conditions of defence and of existence. In places where until then a hurried visit with an experienced guide seemed a bold feat, in regions where there was perhaps one isolated Alpine hut in which it was considered an ordeal to spend one or two nights, there were constructed hutments, telegraph and telephone offices, infirmaries, workshops and stores. In such places, at a height of over 3,000 metres, tens of thousands of men spent several winters. To prepare these encampments both for shelter and for defence, it became necessary to excavate in the rock an enormous quantity of vast caves. In some places an underground city was cut in the rock with inter-communicating caves