﻿Notices respecting New Books. 447 



a special service to this branch of electrical science in collecting 

 the material for this textbook. Needless to say it is well done. 

 It begins with a mathematical introduction which gives in a simple 

 way the properties of vectors and their functions, leading up to 

 the hyperbolic functions so successfully introduced by Professor 

 A. E. Kennelley into the subject of alternating currents. Indeed, 

 the book mijuht almost be considered on its more theoretic side an 

 exposition of Professor Kennelley 's methods, so thoroughly is it 

 saturated with them. These methods reduce to comparative 

 simplicity the pioneer but elaborate investigations of Oliver 

 Heaviside and Pupin on telegraphic and telephonic transmission. 



The book is not, however, a merely abstract mathematical 

 exposition. After the introduction it gives a thorough treatment 

 of the many practical problems which have arisen, each one worked 

 out numerically with reference to actual cables. The student is 

 thus provided with a safe grounding by which he will be enabled 

 to understand existing practice in such an intelligent w 7 ay that he 

 mav well hope to advance beyond it by performing pioneer work 

 himself. 



Dr. Fleming is always happy in his exposition. Where diffi- 

 culties and intricate points exist he is ready with an apt illustration. 

 Numerous examples of this might be quoted from the present 

 volume. 



The book is excellently edited ; we can find only a few trifling 

 misprints. We are astonished, however, to find distortion spelt 

 uniformly with s instead of the second t. Surely this is not in 

 accordance with common practice. It is not English ; nor w r as 

 the change introduced when the word was made a technical word 

 by Heaviside. 



Bulletin of the Bureau of Standards. Vol. 7, No. 3. Washington : 



Government Printing Office, 1911. 

 This part contains some quantitative experiments in Long- 

 distance Eadiotelegraphy by L, W. Austin, being an account of 

 experiments made by the American Navy Department between 

 the scout-cruisers ' Birmingham ' and ' Salem ' and the large 

 Eessenden station at Brant Bock. Erom these experiments the 

 following equation is deduced for over-sea transmission : — 



. o-IsM, / '0015 17\ 



where Ir and Is are received and sending currents, \ \ are 

 antenna heights, X is the wave-length, and d the distance apart, 

 all lengths being given in kilometres. Messrs. E. Buckingham 

 and J. II. Dallinger describe an extension of Paschen's method of 

 equal ordinates to the computation of the constant C„ of Planck's 

 equation of radiation. It is shown that with sufficient accuracy 



x x r / c - - c ^ \ "i 



