September 22, 192 1] 



NATURE 



III 



elaborate (probably on account of post-war con- 

 ditions), but they are sufficient. The whole subject 

 is one of great interest. Stereoscopic instruments 

 have now got well beyond the curious toy stage, 

 and have many applications of precision, not the 

 least of which is to range-finders, of which the 

 Germans appear to have made considerable use. 



The value of such a historical monograph, espe- 

 cially with the excellent index of names and refer- 

 ences at the end, is very great. To anyone 

 desirous of acquiring rapidly knowledge of a 

 subject for research purposes, it means an in- 

 credible saving of time and labour. It is also an 

 aid to research in another way, by unearthing a 

 number of results long forgotten, from which 

 many a valuable hint can be gleaned. For the 

 lack of work of this kind far too much of the 

 time of men of science nowadays is spent on re- 

 discovery. L. N. G. F. 



Kite Balloons. 



The Design and Stability of Streamline Kite 

 Balloons, with Useful Tables, Aeronautical and 

 Mechanical Formulae. By Capt. P. H. Sumner. 

 Pp. viii-(- 146. (London : Crosby Lockwood and 

 Son, 1920.) los. 6d. net. 



WHILE a vast literature has grown around 

 aeroplanes since the outbreak of the war 

 gave an unprecedented stimulus to aeronautical 

 theory and practice, and a certain amount has 

 been written about airships, very little indeed has 

 seen the light of publication in connection with 

 balloons. Popular interest was attracted to the 

 more spectacular phases of flight; the Zeppelin 

 raids dominated the minds of millions of non- 

 combatants in the early part of the war, and the 

 aeroplane raids captured their minds later on. To 

 the active service man who was inclined to join 

 the Air Force the aeroplane gave promise of 

 excitement and distinction; to the scientific in- 

 vestigators at home the aeroplane and airship 

 presented many problems of baffling difficulty and 

 interest. The kite balloon, on the other hand, 

 never reached such heights of popularitv. Its 

 work was more useful than spectacular; ever 

 shrouded in secrecy, it scarcely ever attracted the 

 attention of any who were not immediately 

 engaged in its construction or its use. 



A certain amount concerning the kite balloon 

 is to be found in such a book as Bairstow's 

 "Applied Aerodynamics," but it seems that Capt. 

 Sumner's is the first separate book on the subject, 

 at least in English. The author takes as model a 

 balloon of capacity 670 cubic metres, which can 

 rise to a height of 2500 ft. with one observer, 

 NO. 2708, VOL. I08I 



and a suitable amount of ballast. By means of 

 proportional rules other sizes can be readily calcu- 

 lated. 



First the functions of the various parts of the 

 kite balloon are explained, and then the aero- 

 dynamics are dealt with, leading up to the equi- 

 librium problem. Longitudinal stability comes 

 next, but the stability considered is statical, not 

 dynamical; this ensures great simplification, of 

 course, but something might have been said about 

 the justification for using it. Chapters follow on 

 the effect of the wind, tension in the material of 

 the balloon, the valve, the envelope and rigging. 

 There is, finally, a short account of meteorological 

 balloons. 



Much useful information is contained in the 

 appendix, which is, however, rather miscellaneous 

 in character. One wonders whether a man 

 capable of following the reasoning in such a book 

 needs an appendix containing the formula for the 

 area of a circle or the definitions of the trigono- 

 metrical ratios. S. Brodetsky. 



Our Bookshelf. 



Airman's International Dictionary : Including the 

 Most Important Technical Terms of Aircraft 

 Construction, English, French, Italian, German. 

 By Mario Mele Dander. Pp. vii-h 227. 

 (London : Charles Griffin and Co., Ltd., n.d.) 

 65. 



Aviation for commercial purposes has failed to 

 develop in the manner that was anticipated, yjet 

 several regular air services have come into exist- 

 ence, and if the evolution of civil aeronautics is 

 slow, we can have no reason to doubt the ulti- 

 mate emergence of the aeroplane and airship as 

 standard means of locomotion. There is therefore 

 complete justification for the assertion in the pub- 

 lishers' note that "... there is urgent need for a 

 handy dictionary which will enable a flying man 

 to make his needs and desires known in what- 

 ever country he may land." The dictionary was 

 printed in Italy, and Messrs. Griffin have secured 

 copies for issue in this country. It forms an 

 eminently useful handbook, not only for the pilot, 

 but also for the student and researcher, who often 

 have to consult literature in foreign languages 

 and deal with terms which are too recent for the 

 standard dictionaries. 



The dictionary gives the important technical 

 terms in connection with aeroplanes and airships, 

 as well as with aeroplane and airship construc- 

 tion. There is a "one alphabet" index for all 

 four languages, thus saving much time in the 

 search for the meaning of anv term. 



In a book of this kind mistakes and misprints 

 are to be expected, and it is to be hoped that in 

 a future edition experts in the various languages 

 will be called in to revise the terms. Thus anv 



