March 30, 191 1] 



NATURE 



139 



only been expatiated on here in order to point a 

 moral. On his main subject Mr. Hasluck is abso- 

 lutely trustworthy, and has produced a book which 

 is a credit to himself, to the British School at Athens, 

 and to the University of Cambridge. 



H. R. Hall. 



RADIOTELEGRAPHY. 



Jahrbuch der drahtlosen Telegraphie und Telephonie. 

 Band iii., Hefts i-6. Pp. 1-634. (Leipzig: Johann 

 Ambrosius Barth, 1909-10.) 



FOR those who wish to keep pace with the rapid 

 theoretical and practical progress that is being 

 made in wireless telegraphy, this Jahrbuch is almost 

 indispensable. It contains full accounts of many im- 

 portant researches, abstracts of othei's, and each num- 

 ber gives a very complete bibliography of the litera- 

 ture on the subject, also a brief account of recent 

 patents. 



Glancing through the pages of the present volume, 

 we are impressed with the great improvements that 

 have been made in quantitative measurements. The 

 phenomena dealt with are exceedingly complicated, 

 and as a time interval of one-millionth of a second is 

 long, the inertia of ordinary matter makes it 

 mechanically impossible to follow the rapid changes 

 that take place in an oscillating circuit. Fortunately, 

 the inertia of a kathode stream is practically negli- 

 gible, and the Braun tube is, in consequence of this, 

 very frequently used in researches on electrical oscilla- 

 tions. This instrument has been utilised by Vollmer 

 in an elaborate investigation of the Poulsen arc (pp. 

 ^^7~74» 213-50), and by Roschansky in a shorter series 

 of experiments on spark gap resistance (pp. 21-57). 

 PVom both papers it is evident that much remains to 

 be done before a satisfactory quantitative theoretical 

 explanation of the behaviour of arcs and sparks can 

 be given. 



There are several papers on the mathematical theory 

 of coupled circuits. Mackii criticises the work of 

 Cohen, discusses the theory of the Fischer method for 

 fxamining the two waves in coupled oscillators, and 

 gives some approximation formulae of his own. 

 Berthenod compares direct and inductive coupling 

 mathematically, a problem of particular interest at the 

 present moment. 



The problem of long-distance transmission has 

 brought forth many mathematical discussions of the 

 diffraction of electromagnetic waves; one by H. 

 I'oincar6 appears in the present volume. But it is 

 doubtful whether diffraction plays a very important 

 part ; a highly conducting layer of air in the upper 

 regions of the atmosphere would probably be a much 

 more important factor. Very little has so far been 

 published regarding long-distance transmission. 

 Surely a large number of valuable statistics must have 

 been gathered during the past few years at powerful 

 wireless telegraph stations, like Marconi's trans- 

 atlantic stations, the publication of which would be 

 of the greatest theoretical and practical interest. 



Only three papers appear from English men of 

 NO. 2 161, VOL. 86] 



science — one by Lodge and Muirhead on "The general 

 principles of syntonic wireless telegraphy " ; a second 

 by Fleming, "Some quantitative measurements in 

 radiotelegraphy " ; and a third by N. Campbell on 

 "The aether." 



Wireless telegraphy seems to be very much neg- 

 lected by the technical colleges in this country ; which 

 is most regrettable, as probably in no other branch of 

 engineering is it so essential that an original investi- 

 gator should have such a very thorough grasp of the 

 fundamental principles of physics. 



MODERN ENGINEERING ACHIEVEMENTS. 



Engineering of To-day. By T. VV. Corbin. Pp. 

 xvi + 367. (London : Seeley and Co., Ltd., igii.) 

 Price 55. net. 



THE author of this book has set himself the task 

 of giving a popular account of the present 

 developments of engineering science, illustrating his 

 text with diagrams and photographs, and, although 

 he has not attempted to make any rash forecasts, yet 

 he has indicated the directions in which future de- 

 velopments are likely to occur. 



The first few chapters are devoted to the various 

 sources of power ; the steam engine, the gas engine, 

 and hydraulic motors, are all in turn dealt with ; 

 then follows a chapter on how this power is trans- 

 mitted, special attention being devoted to electrical 

 methods. The author next treats of the materials used 

 by the engineer, and modern methods of manufacture. 

 In describing the cantilever system of bridge con- 

 struction, it is a pity that the author did not adopt 

 the elegant illustration given by the late Sir Benjamin 

 Baker in the course of a popular lecture on the design 

 of the great structure across the Firth of Forth. Ship 

 construction is explained somewhat fully, and a clear 

 account is given of the structural design of most of 

 the leading types of passenger and cargo boats; to 

 ships of war a special chapter is devoted, and, as an 

 illustration of the most modern type of battleship, 

 the author has selected the Minus Geraes, recently 

 built by the firm of Sir W. G. Armstrong, Whitworth 

 and Co. for the Brazilian Government. Submarine 

 work and submarine diving form the subject of an- 

 other chapter. 



A short account is given of the filtration of water 

 prior to its distribution to the consumer, but no men- 

 tion is made of the system of mechanical filtration, 

 which has recently been extensively adopted. As an 

 illustration of a great water scheme, the author has 

 selected the Coolgardie water supply, probably the 

 most daring scheme ever conceived, and onr whuh 

 has proved entirely successful- 

 Three excellent chapters are those devoted to r.iil- 

 ways and their work; a description is given df ilic 

 construction of a modern express locomotive, .md 

 details as to the signalling appliances wliidi Ikivc to 

 be adopted in order to secure the safety of trains on 

 lines crowded with trafiic. 



That the book is quite up to date is proved by the 



