466 



NATURE 



[September 15, 1898 



cultivation. Among them is D. nobile, which, being 

 beautiful and of easy growth, is universally cultivated. It 

 was introduced from China about sixty years ago, and has 

 been figured many times. 



Mr. Pantling's Nepaulese lads have done so well that it 

 is hardly gracious to find fault with them. But the figures 

 of the more showy Dendrobia illustrate a defect which 

 detracts somewhat from the artistic value of some of the 

 plates. The defect referred to is a want of brilliancy of 

 colour — the tints are too sober. This may be due to 

 the colour wash being too thin, having regard to the 

 lithographic drawing it has to cover. 



Plate 285 represents the small local form of Vauda 

 teres. This plant, one of the most beautiful of the 

 Orchidese, produces, as found in cultivation, flowers fully 

 twice the size. V. teres crossed with its near Malayan 

 ally, V. Hookert, has produced V. ^^ Agnes Joachim" 

 which carries a 12 to i6-fl[owered raceme. 



Plate 445 represents, growing on a stone, a very 

 striking orchid, Diplomeris hirsuta, which, besides its 

 remarkable mode of growth and beautiful flower, is of 

 great botanical interest, as in it " is indicated with com- 

 parative clearness a theory of the structure of the flower 

 of the Ophrydeas," explained in the Introduction. 



Sir George King is so eminent a botanist and so high 

 an authority on the Orchidese that his conclusions will 

 doubtless meet with general acceptance. Yet it is some- 

 what difficult to accept the view that Dendrobium 

 Jenkinsi, Wallich, pi. 85, is not a good species. Under 

 cultivation it differs widely from D. aggregatwn in bulb, 

 mode of growth, and inflorescence. The sub-genus 

 Pleione is merged in Coelogyne, but the Pleiones seem 

 sufficiently distinct in bulb and leaf habit, and flower, 

 fully to justify the retention of the sub-genus. Again, it 

 would appear to be intended to merge Thunia in Phaius, 

 from which it differs in having no pseudo-bulbs, but leafy 

 stems with a terminal inflorescence. Phaius albus, pi. 

 153, seems to be Thunia Marshalliana, Rchb. f., which, 

 when gathered on oaks in the Kangra valley at an 

 elevation of 4000 to 5000 feet, flowered profusely in a 

 verandah at Dharmsala. 



It should be mentioned that this volume is dedicated 

 to our great botanist. Sir Joseph Hooker. It forms a 

 valuable contribution to the botany of the natural order 

 it deals with, and reflects great credit on the care, skill, 

 energy and enterprise of its authors. Moreover, the 

 careful notes at the end of each botanical description 

 are a useful help to the cultivator. 



OUR BOOK SHELF. 



Essai sur la Theorie des Machines electriques ci Influence. 

 By V. Schaffers. Pp. 139. (Paris: Gauthier-Villars 

 et Fils. Brussels : Polleunis and Ceuterick, 1898.) 



This is an important monograph on the history and 

 theory of the influence electrical machine. It is now a 

 good deal more than a century since Wilke invented the 

 electrophorus ; the apparatus was improved by Volta, 

 and in 1786 the principle was utilised by Bennet in the 

 " doubler." There confusion begins : machines are re- 

 discovered, re-improved, re-named ; and men of science 

 of all nationalities make claims for the rights of priority. 

 The author maintains his opinions unbiassed through all 



NO. 1507, VOL. 58] 



these historical predicaments, and deals equally fairly 

 with Holtz, Voss, and Wimshurst. The theory of the 

 two generic types of influence machines is dealt with at 

 considerable length, and some account is given of the 

 " water-dropping " apparatus, and its application to cloud 

 formation. This part of the subject might with advan- 

 tage be extended to include the beautiful experiments of 

 Lord Rayleigh on the electrification of liquid jets. 



An Introductory Course of Practical Magnetism and 

 Electricity. By J. Reginald Ashworth, B.Sc. (Vict.). 

 Pp. xii -t- 84. (London : Whittaker and Co., 1898). 



If testimony were needed of the increasing recognition 

 of experimental work in physics as a valuable factor in 

 education, it would be found in the large number of text- 

 books recently published for the use of students in 

 physical laboratories. The present manual comprises a 

 series of practical exercises, by the performance of which 

 the young student will add to his stock of real know- 

 ledge, and qualify himself to carry on more difficult ex- 

 periments when he advances to the higher stages of his 

 subject. The book is intended for use in the laboratory, 

 the course in it being supplementary to the theoretical 

 teaching of the class-room and class-book. The ex- 

 periments cover the subjects of the elementary stage of 

 magnetism and electricity of the Science and Art De- 

 partment ; they are concisely described, and can be 

 successfully done with simple and inexpensive apparatus. 

 These characteristics are sufficient to commend the 

 volume to the attention of teachers in technical and 

 other schools. 



Photography Annual : a Compendiwn of Photographic 

 Information, with a Record of Progress in Photography 

 for the past Year. Henry Sturmey, editor. Pp. cxlvi 

 -I- 722. (London : IlifFe, Sons, and Sturmey, Ltd., 

 1898.) 



To the photographer, be he professional or amateur, 

 who desires to keep in touch with the progress of the 

 science and art of photography, and to know what novel- 

 ties there are in the market, this volume is almost 

 indispensable. It contains tables of reference and other 

 useful information for photographers ; a list of photo- 

 graphic societies ; selected articles upon practical sub- 

 jects by experienced photographers ; a record of progress 

 in the various branches of the science and practice of 

 photography during the year 1897 (including photo- 

 graphic chemistry), photographic optics, astronomical 

 photography, photographic mechanical printing, and 

 other applications of photography (including Rontgen 

 photography). Each of these articles is a very valuable 

 summary of scientific work published last year upon 

 subjects related to photography, and results obtained by 

 the aid of photography. In addition to these service- 

 able abstracts, the volume contains notes on novelties in 

 photographic apparatus and materials, optical lanterns 

 and related appliances, and several excellent specimens 

 of process work as illustrations. 



Botanisches Bilderbuch filr Jung und Alt. By Franz 

 Bley. Part ii. With explanatory text by H. Berdrow. 

 Pp. viii -f- 192. 24 Plates. (Berlin : Gustav Schmidt 

 (formerly Robert Oppenheim), 1898.) 



The first part of this work, containing coloured pictures 

 of plants obtainable in Germany during the opening half 

 of the year, has already been noticed in these columns ; 

 the present part contains 216 pictures upon 24 plates 

 arranged in the order of the months in which the plants 

 appear, from June to September. The pictures are in 

 most cases well coloured, and, in conjunction with the 

 explanatory notes referring to them, will assist and 

 encourage the study of outdoor botany. 



