November 15, 1900] 



NATURE 



55 



cases as though it were an indifferent gas ; that the 

 concentration of the dissociated portion of a salt may 

 be substituted fur the total concentration ; iSic, &c. The 

 result is that our calculations apply at best only to limit- 

 ing or ideal cases, where an error in deducing the for- 

 mula may be masked by the error of observation. 

 Helmholtz did not do this, but Helmholtz is considered 

 old-fashioned." 



What Mr. Bancroft would have us do is to study con- 

 centrated solutions. The object is most laudable ; but 

 until a Helmholtz appears who is capable of attacking 

 the problem in all its complexity, physical chemists will 

 probably continue their work on dilute solutions, for 

 which the conditions are comparatively simple, and the 

 behaviour of which is represented closely by the results 

 deduced from a consideration of the limiting or ideal 

 cases above referred to. 



There is one point about many of the reviews (and 

 some of the original contributions) which calls for 

 remark — they seem needlessly scathing. Should any one 

 be so unfortunate as to differ in opinion from the reviewer, 

 he is forthwith tomahawked, and his scalp brandished 

 in triumph before the horrified reader. It is painful to 

 see one's friends — nay, even one's enemies — ruthlessly 

 butchered in this fashion, and we would earnestly counsel 

 a less close adherence to the former methods of the 

 Wild West. J, W. 



THE EXPLORATION OF THE UPPER AIR. 

 Sounding the Ocean of Air. Being six lectures delivered 

 before the Lowell Institute of Boston in December, 

 1898. By A. Lawrence Rolch, S.B., A.M. " Romance 

 of Science" Series. Pp. viii -f 184. (London : Society 

 for Promoting Christian Knowledge, 1900.) 



A CORDIAL welcome for this little book may be 

 anticipated from the fact that it is the latest addition 

 to the series which has given us Boys's " Soap Bubbles," 

 Perry's " Spinning Tops," Worthington's " Splash of a 

 Drop" and Sir R. Ball's ''Time and Tide." Its author 

 has won for himself a prominent place among those who 

 are best acquainted with modern ways of sounding the 

 ocean of air, by the work done at his observatory at Blue 

 Hill, Massachusetts, and by his personal association with 

 the observers of clouds and the users of balloons and 

 kites in Europe. 



Perhaps the very width and depth of his acquaintance 

 with the details of the subject have made the task of the 

 popular exposition of it in six short chapters a difificult 

 one. The procession of facts, each one of great interest 

 in itself, is apt to become panoramic and even kaleido- 

 scopic ; and when^one page, or sometimes one paragraph, 

 has to accommodate a succession of scientific ideas, the 

 inexpert reader may find himself a little bewildered with 

 the rapidity of the transitions, and occasionally even with 

 some short cuts to scientific conclusions. 



After a short historical introduction the book deals 

 successively with the exploration of the upper air by 

 means of clouds, balloons and kites. Each section gives 

 a brief account of the earlier experiments, before treating 

 of the recent results. The romance begins in the first 

 chapter with a striking diagram of the heights of certain 

 observatories, mountain peaks, kites and balloonsj 

 showing one balloon — an unmanned one, be it said — 

 NO. f620, VOL. 63] 



at the almost incredible height of 13 miles or more 

 (upwards of 70,000 feet), where the corresponding 

 barometric pressure is about one and a half inch of 

 mercury ; it culminates in the chapter describing 

 these extremely lofty ascents. The chapters on the 

 various types of balloon, captive balloons, free balloons 

 and ballons sondes (unmanned balloons) are, both from 

 the historic and the scientific point of view, the most 

 interesting to the general reader. The study of clouds 

 is clearly too large a subject for a single chapter ; and 

 the final chapters, which are devoted to the description 

 of kites and the results obtained at Blue Hill, enter into 

 details which the meteorologist will find of great value 

 and interest, but which require close attention from the 

 reader. The diagrams with which the book is illustrated 

 have suffered a little from the reduction in scale for the 

 purpose of reproduction ; but the reader who will take 

 the trouble to follow them carefully with the text will be 

 rewarded by obtaining an excellent survey of the work 

 done with kites up to a height of 12,000 feet, and some 

 idea as to what they may be expected to accomplish in 

 the future. 



One side of the romance of kite work is only touched 

 with a light hand. The Berlin experimenters could supply 

 at least one thrilling story of a kite that absconded for 

 the night with its wire, and made a long and very event- 

 ful journey ; but Blue Hill has perhaps been more 

 fortunate ; doubtless its situation lends itself less easily 

 to romantic exploits of that description. 



It is interesting to notice the geographical distribution 

 of the work of exploring the upper air as it appears in 

 Mr. Rotch's account. Speaking quite generally, the 

 United States are conspicuous for the work with kites, 

 Germany for various forms of manned balloons, and 

 France for ballons sondes, although the most adventurous 

 of these last, the " Cirrus," belonged also to Berlin ; while 

 cloud work is more evenly distributed, the services of 

 Hildebrandsson in that department render Sweden con- 

 spicuous. Great Britain is credited with an active share 

 in the initiation or early development of the scientific 

 exploration of the air by clouds, balloons and kites in 

 turn, but in later years seems to have withdrawn from 

 such enterprises. 



Mr. Rotch's interesting lectures may well leave the 

 impression that the further sounding of the upper air of 

 the British Isles might be exciting on account of the 

 special situation and circumstances of the islands, but, 

 for the same reason, would be of great scientific 

 importance. 



OUR BOOK SHELF. 



The Locust Plague and its Suppression. By yEneas 

 Munro, M.D., Edinb. and Cordova, Fellow of the 

 Faculty of Physicians and Surgeons of Glasgow. 

 With illustrations. Pp. xvi -|- 365. (London : Murray^ 

 1900.) 

 The volume before us has been prepared by the author 

 after nearly ten years' observation of locust ravages in 

 the Argentine Republic and in South Africa. He is pro- 

 foundly convinced of the enormous damage caused by 

 locusts in various parts of the world, and has brought 

 together a considerable amount of information respecting 

 the various means which have been adopted for destroying 

 them. Dr. Munro writes from a practical point of view, 



