166 



DISCOVERY 



Books Received 



(Mention in this column does not preclude a review.) 

 LANGUAGE AND LITERATURE 

 A History of Modern Colloquial English. Bj- Prof. 

 Henry Cecil Wyld. Second Edition. (T. Fisher 

 Unwin, Ltd., 25s.) 



MISCELLANEOUS 

 The Yearbook of the Universities of the Empire, 1922. 



Edited by W. M. Dawson, and published for the 



Universities Bureau of the British Empire. (G. 



Bell & Sons, Ltd., -js. 6d.) 

 The Apple-Tree. By L. H. Bailey. (The Open Country 



Books published by the Macmillan Company, New 



York, ys.) 

 Materials for the Study of the Apostolic Gnosis. By T. S. 



Lea, D.D., and F. B. Bond, F.R.I.B.A. In two 



parts. (Oxford : Basil Blackwell, 6s. each part.) 

 The Evolution of Civilisation. By Lord Clifford, F.G.S., 



etc. (The Evolution Society, 67 Madeley Road, 



Ealing, W.5, 5s.) 



PSYCHOLOGY AND PSYCHICAL RESEARCH 



Introductory Lectures on Psycho-Analysis. By Prof. 



SiGMUND Freud, M.D., LL.D., Vienna. Trans. 



by Joan Riviere. With a Preface by Ernest Jones, 



M.D. (George Allen & Unwin, Ltd., i8s.) 

 Revelations of a Spirit Medium. By H. Price, F.R.M S., 



and E. J. Dingwall, M.A. (Kegan Paul, Trench, 



Triibner & Co., Ltd., 75. 6d.) 

 A Unique Heathen, to which is now added Theodore 



Schroeder on the Erotogenesis of Religion. Nancy 



E. Sankey-Jones. (Cos Cob, Conn, U.S.A.) 



SCIENCE 

 Einstein and the Universe. By Charles Nordmann. 



Trans, by Joseph McCabe. With Preface by the 



Rt. Hon. The Viscount Haldane, O.M. (T. Fisher 



Unwin, Ltd., 105. 6d.) 

 A Criticism of Einstein and His Problem. By W. H. \'. 



Reade, M.A. (Oxford : Basil Blackwell, 4s. Orf.) 

 The Structure of the Atom. By Stephen Miall, B.Sc, 



LL.D. (Benn Brothers, Ltd., is. 6d.) 

 Calculus and Graphs. By Prof. L. M. Passano. (New 



York : The Macmillan Company, gs.) 

 Protein Therapy and Non-Specific Resistance. By William 



F. Petersen, M.D. With an Introduction by Prof. 

 Joseph L. Miller, M.D. (New York ; The Macmillan 

 Company, 21s.) 



Pasteur and His Work. By L. Descour. Trans, by 

 A. F. and C. H. Wedd, M.D. (T. Fisher Unwin, Ltd., 



Correspondence 



THE INVENTION OF THE PILOT CABLE 



To the Editor of Discovery 

 Sir, 



Mr. George Frederic Lees contributed to the March 

 number of Discovery an extremely interesting article on 



Wireless Navigation and Nocturnal Flight, in which 

 certain ingenious devices of M. Loth were described. 

 In this article mention is made of " M. Loth's first in- 

 vention, that of the cable guide for ships entering difficult 

 harbours," and the writer proceeds to give " a short 

 account of tliis electrical discovery wliich is already being 

 exploited commercially." Now the Leader Cable, which 

 is the recognised English name for what the French call 

 the Cable Guide, was used by our own Admiralty dxiring 

 the war, while the system itself was invented and used 

 experimentally as early as 1891 by Charles A. Stevenson, 

 F.R.S.E., M.Inst.C.E., Ass.M.Inst.E.E. Mr. Lees is 

 evidently wholly ignorant of Dr. Drysdale's Kelvin 

 Lecture on " Modern Marine Problems in War and 

 Peace," published in the Journal of the Institute of 

 Electrical Engineers in July 1920, and of a later article 

 in Nature of February 10, 1921, where the use of the 

 Leader Cable is fully explained. In both of these articles 

 Prof. R. S. Owen of McGill University is mentioned as 

 having devised the same system in igoi or 1903. My 

 purpose, however, is to bring out clearly the fact that to 

 Mr. Stevenson we owe, not only the first conception of the 

 method and the first practical demonstration of its effi- 

 ciency, but also the first published description of it. In 

 1 89 1 he exhibited his apparatus in action to the Com- 

 missioners of the Northern Lighthouses, his express pur- 

 pose being to lay an electric cable from a port to the open 

 sea so as to pilot vessels into harbour. The method was 

 described in a paper read before the Royal Society of 

 Edinburgh on January 30, 1S93, ■ind published in that I 

 Society's Proceedings, vol. xx, 1892-95, p. 25. Mean- 

 while he had taken out a patent for the Pilot Cable, of 

 which more hereafter. He continued working at the 

 problem with practically no encouragement from others, 

 and in Nature of December 31, 1896, he stated as an 

 experimental result that signalling was effective at 200 

 yards distance from the cable. This was before the days 

 of sensitive electrical detectors. In 1897 Mr. Stevenson 

 constructed a working model representing his system in 

 action on the French Coast in the neighbourhood of Ushant, 

 and showing how a protecting cable could be used elec- 

 trically to warn vessels (provided with suitable detectors) 

 when they were approaching a dangerous shore. The 

 model is still on exhibition in the Royal Scottish Museum, 

 Edinburgh. 



I propose now to reproduce the description given in 

 Mr. Stevenson's patent of 1S93 and compare it with the 

 corresponding section in Vice-Admiral Fournier's Report 

 on M. Loth's work to the French Academy of Sciences 

 last year. The complete Specification of Mr. Stevenson's 

 patent, which was accepted on March 4, 1893, is as 

 follows : — 



" X Means of Indicating Electrically the presence of 

 a Coast, Rocks or Shoals, or determining a Ship's Position 

 in a River, Estuary or Sea. 



" Charles Alexander Stevenson, Civil Engineer, 84 

 George Street, Edinburgh, do hereby declare the nature 

 of this invention and in what manner the same is to be 

 performed, to be particularly described and ascertained 

 in and by the following statement : — 



