202 



NATURE 



[November 15, 1917 



Fourier series, each term of which has an ex- 

 ponential factor. It is, therefore, much more 

 unmanageable. 



If we except Dr. Fleming's introductory text- 

 book, this treatise is the first to give a complete 

 account of the electrical theory of the transmis- 

 sion of signals along a submarine cable. The 

 industrious student, provided he has a good mathe- 

 matical foundation on which to build, can readily 

 acquire the whole practical theory from this work. 

 He will also find suggestions for improved methods 

 of submarine telegraphy and for improving cables, 

 both of which are very promising subjects for 

 further mathematical and physical research. 

 Hitherto radio-telegraphy has acted largely as a 

 "feeder" for the submarine cable companies. 

 After the war it is unlikely that the radio-tele- 

 graphists will be content to play this subsidiary 

 rdle. Cable engineers, therefore, are alive to the 

 necessity of making continual improvements in 

 their methods, and a book like Dr. Malcolm's 

 should prove a great help to them. 



In the earlier portions of the book a resumi is 

 given of the necessary mathematical theorems. 

 The complete solutions are also given of the funda- 

 mental equations of transmission, particular stress 

 being laid on the transient phenomena. Perhaps 

 the treatment in this portion of the book is a 

 little too modern. It is very tempting to define 

 the sine and cosine functions by means of series, 

 but to prove that they are periodic functions of 27r 

 is extremely difficult. The author's proof, although 

 ingenious, is not rigorous. The values of the 

 ordinates of the sine and cosine curves are 

 obviously not calculated from the series. The 

 ordinary clumsy geometrical definitions of the 

 hyperbolic sine and cosine might have been omitted 

 with advantage. The negative sign in Formula 44 

 is inadmissible, but this does not follow from the 

 proof given. The statement that the root with the 

 negative sign is either less than zero or negative 

 is rather quaint. On p. 299 we come across a 

 divergent series due to Heaviside, and we are 

 told that it is to be taken as far as its smallest 

 term. As this needs explaining, we turn up 

 Heaviside and find that the only comment he 

 makes on it is that it is lucky that it is divergent. 

 A reference to a book on modern analysis such as 

 Whittaker and Watson's would, in this connec- 

 tion, be a help to the student. 



As to the author's nomenclature, definitions, 

 and mathematical methods we have only minor 

 criticisms to offer. The numerous and excellent 

 diagrams illustrating the formulae are worthy of 

 the highest commendation. The calculation of all 

 the curves shown must have required a great deal 

 of labour. We can heartily recommend the book 

 to cable and telephone engineers and to physical 

 mathematicians desiring subjects for research. 

 The Committee of the Privy Council for Industrial 

 and Scientific Research would, in the reviewer's 

 opinion, be well advised to give grants to en- 

 courage mathematical research on some of the 

 problems discussed by Dr. Malcolm. 



(2) This book is not written for the designer. 

 NO. 2507, VOL. 100] 



It is written, we are told, for the engineer who is 

 responsible for the working of the machinery, and 

 for ithe purchaser who pays the bills and seeks the 

 profit. The special features of the book are the 

 numerous questions and problems scattered 

 throughout the text and the summaries in large 

 type of the contents of the various chapters. The 

 results given are trustworthy -ind can be 

 easily understood by readers with very Umited 

 mathematical knowledge. Occasionally the authors 

 seem to get a little weary. The appendix, for 

 instance, refers us to p. 54 for a mention of the 

 Tirrill voltage regulator. We are there told that 

 it "is rather a complicated device involving the 

 interaction of solenoids, differential magnets, 

 levers, and contacts which it is not in the province 

 of this book to describe, as no new principles are 

 to be learned thereby." If we insist, however, on. 

 knowing about it, we are told to secure the " bul- 

 letins and instruction sheets " of the General Elec- 

 tric Company. After saying all this, the principle 

 is described quite satisfactorily. 



We wonder what the old-fashioned Cambridge 

 don would have said to this question (p. 150) : 

 " How many dollars less per year does it cost to 

 operate a 50 kv.-a., type S transformer (Table A) 

 than a 50 kv.-a., type SA transformer? How 

 many dollars more can we afford to pay for the 

 ' S ' than for the ' SA ' ? " Apart from the word- 

 ing, it is really a very admirable question, teach- 

 ing the student how to study a maker's catalogue 

 intelligently. An excellent feature of the book is 

 the stress laid on the distinction between 

 "economy" and "efficiency." The most efficient 

 apparatus is by no means the most economical, as 

 the first cost and maintenance expenses have to 

 be taken into account. This very obvious con- 

 sideration is often neglected by beginners. 



It may be more logical to talk about capacitance 

 than about capacity, but when the word is re- 

 peated twenty-two times on one page (p. -^76) it 

 gets very monotonous. The authors should have 

 stated that the model to represent the capacity 

 of a transmission line fo. 376) is applicible only 

 when the load is balanced. A. Russkll. 



THE THYROID GLAND. 

 The Thyroid Gland in Health and Disease. By 

 Major R. McCarrison, I. M.S. Pp. xvii + 286. 

 (London : Bailli^re, Tindall, and Cox, 1917.) 

 Price 12s. 6d. net. 



T N^ this well-appointed volume, with excellent 

 *- illustrations, Major McCarrison has collected 

 much useful information about the thyroid and 

 parathyroid glands in health and disease. The 

 work is of peculiar value in that the author has an 

 intimate experimental and clinical acquaintance 

 with the subject, and this first-hand knowledge 

 has guided him in discriminating between the 

 many and conflicting theories that have been ad- 

 vanced as to the physiological role of these 

 glands. He is at the saipe time in a position to 

 advance views of his own of far-reaching import- 

 ance. 



