292 



NATURE 



[January 26, 1S93 



department. Dr. Vogel's chief difficulty has beeh to keep 

 the book within reasonable limits while bringing it up to 

 date, but he has not been wholly successful in this. By a 

 slight further enlargement of the book he might without 

 difficulty have very much increased its value. A descrip- 

 tion of the diffraction spectroscope should have been 

 given in the section on spectroscopes ; Prof. Hale's work 

 in photographing prominences and faculas should have 

 been introduced ; the chapter on Mars is very much be- 

 hind the times ; and some details should certainly have 

 been given of the international scheme for photograph- 

 . ically charting the stars. 



Dr. Vogel has considerably altered the arrangement of 

 the chapter on comets and meteors, and this alteration 

 has led to the curious result that the same woodcut 

 appears as Figs. 152 and 165. The chapter on stellar 

 astronomy is also recast, the editor's own latest classi- 

 fication of star spectra being given to the exclusion of 

 all others. The section on variable stars has also been 

 entirely rewritten. These chapters would have been 

 much improved by an account of recent discoveries as to 

 the resemblances between comets, nebulae, and stars, 

 and of the theory that variable stars are formed of revolv- 

 ing swarms of meteorites. The classification of star spectra 

 which recognises an ascending and descending tempera- 

 ture should have been given, and recent work and theories 

 on temporary stars certainly deserved attention. The 

 bibliography given in the first edition has been omitted 

 in the second, as being too much for the general reader, 

 and insufficient for the student of science. The excellent 

 series of biographical notices in the appendix has been 

 carefully extended to 1 891, and completely rearranged. 

 Dr. Vogel has adopted the admirable plan of arranging 

 these notices chronologically in order of death, instead of 

 birth, probably on the grounds that all work is largely 

 the result of previous discoveries, and that the later 

 years of a man's life are usually his best and most pro- 

 ductive. A series of excellent tables and a full index 

 complete the volume. 



The general appearance of the book has been much 

 improved by the use of new woodcuts for the illustrations, 

 and by the substitution of two excellent photographs of 

 nebulae (those of Orion and Andromeda) for the very 

 unsatisfactory star charts of the earlier edition. 



A. T. 



The Hemiptera Heteroptera of the British Islands. By 

 Edward Saunders, F.L.S. (London : L. Reeve and 

 Co., 1892.) 



It is now nearly thirty years since Douglas and Scott 

 first made the study of the British Hemiptera Heterop- 

 tera possible to ordinary students by the publication of 

 a description of these insects in a volume issued by the 

 Ray Society. The difficulties were then very great, for 

 purely insular ideas in entomology were prevalent, and 

 our hemipterous insects had not been sufficiently com- 

 pared with continental species. Douglas and Scott did 

 all that was possible at that time and produced a good 

 work that has held the ground as the best published 

 authority on the subject. Very much, however, has been 

 done since that period, and restricted specialists in ento- 

 mology, as in most other branches of natural science, 

 have exercised unlimited time and patience in studying 

 the classificatory problems of a single family or even of 

 a large genus. Hence in a monograph of to-day the 

 standard of advanced classification and descriptive 

 facility is considerably raised from that which dominated 

 the writings of the earlier authors. Mr. Saunders has 

 not only aimed at this perfection, but has sought to 

 place in the hands of the British student and collector 

 a thoroughly trustworthy handbook by which he may un- 

 derstand and identify his collection, and in this we think 

 the author has altogether succeeded. We must not look 

 for bibliographical references or synonymical notes, the I 



NO. 12 13, VOL. 47] 



names of the describers of families, genera, and species 

 being only indicated, while the habitats of the species 

 are confined to such locaHties in the British Islands as 

 are recorded by collectors ; and this is perhaps all that 

 can be expected in a local monograph. It is there- 

 fore in no spirit of criticism we express a regret that 

 in all faunistic writings the complete recorded distri- 

 bution of the species is not given. Thus even the 

 purely British collector would not be the worse for 

 learning that Zicrona ccerulea, to be found in the suburbs 

 of London, is not only widely distributed throughout the 

 Patearctic region, but is also found in Continental India 

 and in the Malay Peninsula and Archipelago ; or that 

 Ischnorhynchus resedce, to be taken even at Hampstead, 

 is common throughout Europe and Siberia, and is also 

 neither scarce in North nor in Central America. 



We welcome Mr. Saunders's book as a distinct and 

 valuable addition to our insular entomological literature. 

 We also notice that an illustrated edition is advertised, 

 but on the quality of the plates we are compelled to be 

 silent, as the publishers have only forwarded us a plain 

 copy. W. L. D. 



Physical Education. By Frederick Treves, F.R.C.S. 



(London : J. and A. Churchill, 1892.) 

 This essay is reprinted from the "Treatise on 

 Hygiene " by various authors, edited by Stevenson 

 and Murphy, the first volume of which we recently re- 

 viewed (Nature, vol. xlvi. p. 609). It well deserves to 

 be issued separately, for the author has mastered his 

 subject thoroughly, and sets forth his ideas in a plain, 

 straightforward style which will be cordially appreciated 

 by readers who are especially interested in athletics. 

 Mr. Treves is quite as strongly conscious of the evils 

 which may spring from excessive or unsuitable physical 

 exercise as of those which may result from physical ex- 

 ercise being neglected or underrated, so that there is a 

 welcome tone of perfect impartiality in all he has to say 

 about the various ways in which efforts are made to pro- 

 mote health by the use of the muscles. The volume may 

 be confidently recommended to all who desire to under- 

 stand the conditions under which physical exercise is 

 most likely to be of service. 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. '\ 



The Geology of the North-west Highlands. 



In the kindly review of my work by Prof, de Lapparent, 

 which appeared in Nature of 5th inst., there are one or two 

 inaccuracies which I would at once have corrected had I not 

 shrunk from drawing attention, even for purposes of rectification, 

 to an article which I felt to be too eulogistic. Lest, however, 

 my silence be midnterpreted, there is one point on which I wish 

 to say a few words. Prof, de Lapparent, when alluding to the 

 solution of the problem of the geological structure of the North- 

 west Highlands, makes no reference to the distinguished part 

 taken in that subject by Prof. Lapworth. But every one who 

 has followed the progress of geology in recent years is familiar 

 with his work. For myself, I have had no personal share in 

 the discovery. Like most geologists I had accepted the views 

 of Sir Roderick Murchison, and I held to them, until, after the 

 Geological Survey was for the first time extended to Sutherland in 

 1883-84, I was finally convinced that they were untenable by the 

 brilliant mapping of my colleagues, Messrs. Peach and Home, 

 who, following Prof. Lapworth's lead, share with him in the 

 glory of one of the greatest achievements of field geology in 

 recent times. My recantation was published in Nature of 

 November 13, 1884, and the whole history of the investigation of 

 the North-west Highlands up to Prof. Lapworth's latest paper 



