Mabch, 1902.] 



KNOWLEDGE 



G5 



"Ei.KMKMs OF BoTANV." By AV. J. Browne, m.a. Fifth 

 edition. Illustrated. (Heywood.) is. 6d.— This new edition 

 of Mr. Browne's u-seful little primer is considerably enlarged 

 and abundantly illustrated. The greater portion of the book is 

 occupied with descriptive detail. This is well done, and the 

 numerous illustrations which are provided are helpful. AVo 

 fancy the book is intended for the use of students entering for 

 the examinations of the Science and Art Department or other 

 bodies. Were it not so the beginner might find the subject 

 matter more attractive and more living if there were less 

 structural botany and more natural history of plants. We find 

 in the book very little relating to life-histories, or to the rela- 

 tion of ]>lants to their environment. The interesting subject of 

 the dispersal of fruits and seeds is dismissed in a page and 

 a half, while the history and geography of plants on this earth 

 are not touched on at all. Botanical examination papers do not 

 usually err on the side of undue attention to this side of the 

 subject ; yet in the Science and Art and London University 

 |>apers, given at the end of the book, we find elementary 

 questions relative to the dispersal of seeds and the characters 

 of maritime plants that could hardly be answered from this 

 book. Mr. 15rowne's primer is, however, eminently adapted 

 for its purpose : but we would hope that, in the course of time, 

 elementary examination papers on the suljject may deal more 

 with the botany which the child may learn out of doors and by 

 its own observation. 



" Tjik Pko( ess Yeah-Book, 1901 : As Illustrated Review 

 oi- THE CRAPiiif Arts." Kdited by W. Gamble. (Penrose & 

 Co.) — The Annuals, of which this is the seventh, published by 

 Messrs. Penrose, evidence the increasing attention given by 

 the public to book-illustration by the sustained high quality 

 of their reproductions. The various beautifully finished blocks 

 )irinted in one tint or in three colours, which adorn this 

 Annual, cannot fail to afi^ord gre;it jileasure as examples of 

 British workmanship. Xumerons articles are given, exidaining 

 processes and detailing methods by which present results have 

 been reached. These, though very brief, are written by 

 authorities on the several subjects, and adequately fulfil the 

 purpose of an excellent Year-book. 



"Nautical Astkonomv.'' By J. 11. C'olvin, n.A. (Spon.) 

 •2s. 6d. net. — A useful little book, covering the entire course 

 required in the Board of Tnide Examination for Extra Master, 

 as well a.s for the ordinary examinations of that body. It will 

 bo found of service also to the navigating officer as a book of 

 reference. 



"A Recoki) of the Pkogress of the Zoological Society 

 OF London during the Nineteenth Century.'' Edited by 

 the Secretary. — More than half this book is devoted to a list 

 of names of Fellows of the Society. The remainder forms a 

 brief, too brief we consider, but very interesting yearly record 

 of the progress of the societj-. It deals chiefly with important 

 exhibits at the gardens, erection of new buildings, births at the 

 gardens, and a few notes on the society's publications. 



BOOKS KECEIVED. 



Chemitlri/ for Photographers. By Clmrles F. Townsend, F.C.3., 

 P.K.p.s. (Uawbarn & Ward.) Third Edition. Illustrated, ls.net. 



Solar Comtant. By Frank W. Very. (Washington : Weather 

 Bureau.) 



(Jn the Relation of Phyllolaxit to Mechanical Laws. Part II. 

 Asiimmetry and Symmetry. By A. U. Church. (Williams iS 

 Niirgttte.) 59. 



Certain Personal Matters. By H. O. Wells. (Fislier I'nwin.) 



Farm and llomt' Year Book. Tliircl Edition. JUustniti-d. Is. 



Exemplary Sorels. Vol. I. By Miguel de Cervantou. Edited by 

 H. Buxton Forniun. (Gowans & Gray.) Is. net. 



Text-book of Geologi). By Albert Perry Brigham, a.m., f.g.s.a. 

 (Qirschfeld.) 69. net. 



The DUcorery of the Future. By H. G. WelU. (Fisher Unwin.) 29. 



The Procession. February. (Los Angele:.', Cal. : Ueald. ) 10 ct3. 



Report of Weather, Secenbaks, 1901. (\X. W. Wagstaffe.) 



The Aspirate. Bv the Rev. Geoffry Hill. (Fislier L'nniu.) 

 39. fid. net. 



Geoloyii. By Sir Arihibald Geikie, F.RS., &o. (Macmillan.) 

 Illustrated, ,5s. 



Poultry Management on a Farm. By Walter Palmer, Jf.P. 

 (Constable.) Illustrated. Is. 



Jamaica. (Geo. Philip & Son.) 6d. net. 



Selection of Subject in Pictorial Photography. By W. E. Tindall, 

 B.b.a. (Ilifte.) illustrated. 3s.6d.net. 



Journal of the Society of Comparative Legislation, December, 

 190L (Murray.) 58. net. 



Plant Structures. By John M. Coulter, A.M., PH D. (Hirscliteld.) 

 6s. net. 



Plant Relations, liy John M. Coulter, A.M., PU.D. (Hirsclil'eld.) 

 6s. net. 



C. G. S. System of Units. By J. D Everett, M.A., D.C.L., F.E.s., 

 F.R.8.E. (Mai-millan.) 5s. 



Nature's Mysteries. By A. P. Sinnett. (Theosophical Publishing 

 Society.) 28. net. 



Practical Retouching. By Urinkwater Butt, p.b.p.S. (Iliffe.) 

 Is. net. 



English Public Opinion after the Restoration. By Gerald 

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Practical Exercises in Magnetism and Electricity. By U. E. 

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Earli/ Work in Photography. By W. Ethelbert Henry, c.E. 

 (Dawbiirn & Ward.) Illustrated. Is. net. 



Atlas of Practical Elementari/ Zootomy. By G. B. Howe?, U.D., 

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 r. c, F.R.s. (Maeniillaii.) 10s. (id. net. 



British Tyroglyphidic. By Albert D. Michael, F.I.S., F.Z.3., F.B.Ji.s. 

 (Ray Society.) Illustrated. 



♦ 



WING-LINKS. 



By E. A. Butler, b.a., b.sc. 

 In the present paper I propose to deal with the different, 

 devices that are to be found in the structure of four- 

 winged insects, for linking together the fore and hind 

 wing on the same side during flight, so as to produce an 

 increase of power in the simultaneous use of the two pairs 

 of wiugs. The extensive order Diptera, therefore, con- 

 sisting, as it does, wholly of flies which have only one pair 

 of wiugs fully developed, will be outside our present 

 purview. And so equally will the Coleoptera, or beetles, 

 for, although at first sight they appear to have two pairs 

 of wing-like appendages, yet, as only one of these is used 

 for the actual accomplishment of flight, the insects are, for 

 all practical purposes, dipterous. Putting these two great 

 orders on one side, therefore, we find that the rest, with 

 the exception of a few small groups which are apterous, 

 are all four-winged, and use both pairs in flight. Out 

 of this enormous assemblage of four-winged creatures, 

 however, our attention will lie mainly concentrated on two 

 orders, the Hymenoptera and the Lepidoptera, for, with 

 few exceptions, it is iu these two alone that we find any 

 special structures such as are indicated above. 



But, before considering these, there is one group of 

 insects that, for an opposite reason, merits notice because 

 of the entire independence with which the wings work. 

 These are the dragon-flies, the wings of which differ in 

 several important characters from those of most other 

 insects. The power of flight in dragon-flies varies very 

 much. While the larger kinds are extremely jjowerful 

 fliers, and when " hawking " for their prey can go sailing 

 along at a high rate of speed, the smaller and more fragile 

 species have to content themselves with a comparatively 

 weak sort of flutter. In all the species, however, the fore 

 and hind wing on each side are independent of each other; 

 they do not touch, and though they move simultaneously, 

 there is a certain space left between their edges through 

 which the air can pass as the wings move up and down. 

 Again, throughout the Insecta, the secondary, or hind- 

 wings, are generally of a more delicate texture than the 

 primaries, and often smaller iu area, but, if not actually 

 smaller, they yet have to be folded up and tucked away 

 under the primaries when the insect assumes the position 

 of rest. In all these points dragon-flies differ from most 

 other insects. The two pairs of wings are approximately 

 of the same size, and of similar texture, and iu the attitude 

 of rest the secondaries are not folded and packed away 

 beneath the primaries. A large dragon-fly when hunting 

 its prey on the wing must, of course, be able, if it is to be 



