September 17, 1891] 



NATURE 



467 



TELESCOPIC WORK. 

 Telescopic Work for Starlight Evenings. By W. F. 

 Denning, F.R.A.S. (London: Taylor and Francis, 

 1891.) 



A S might be expected from such an experienced and 

 - *- enthusiastic observer as Mr. Denning, this boo'< is 

 thoroughly practical. He is not contented with describing 

 the beauties of the skies, but gives invaluable informa- 

 tion as to how to see them best. The opening chapters 

 give a very complete history of the invention and deve- 

 lopment of the powers of the telescope and its acces- 

 sories. These are followed by chapters on the sun, 

 moon, planets, stars, nebulas, and clusters ; the sun being 

 introduced for the sake of completeness, although not 

 comprehended in the title. The question of the relative 

 advantages of large and small telescopes is discussed at 

 considerable length, and one almost gets the impression 

 that large telescopes, except under very favourable condi- 

 tions, are not desirable possessions. It is very gratifying 

 to note the encouragement given to observers of limited 

 means. To them the book will be of the greatest assist- 

 ance, both in the selection and use of their instruments. 



The author's style is such as to make the book very 

 entertaining as well as instructive. Some of his remarks 

 are well worth quoting, as, for example, his opinion of 

 controversy in scientific matters. 



" Competition and rivalry in good spirit increase 

 enthusiasm, but there is little occasion for the bitter- 

 ness and spleen sometimes exhibited in scientific journals. 

 There are sorne men whose reputations do not rest upon 

 good or original work performed by themselves, but 

 rather upon the alacrity with which they discover griev- 

 ances, and upon the care they will bestow in exposing 

 trifling errors in the writings of their not-infallible con- 

 temporaries. Such critics would earn a more honourable 

 title to regard were they to devote their time to some 

 better method of serving the cause of science " (p. 56). 



Mr. Denning is very emphatic in his opinion that an 

 observer's time is too valuable to be spent in acting the 

 showman to his friends and acquaintances. If all ob- 

 servers were so disposed, there might be reasonable hope 

 for the establishment in this country of some such in- 

 stitution as the Gesellschaft Urania in Berlin, for the 

 special gratification of persons desiring passing glimpses 

 of celestial wonders. 



It is scarcely necessary to say that the chapter on 

 meteoric observations is as good as can be. More ob- 

 servers are undoubtedly needed in this branch of astro- 

 nomy, and volunteers will find very full instructions in 

 the pages of this book. In addition to the notes on 

 variable stars given by the author, we would suggest the 

 tracing of the light-curves of a small number of stars by 

 each observer. Anyone at present attempting to deter- 

 mine the laws governing variability will find such in- 

 formation lamentably deficient. 



The book is full of important practical details, and an 

 appendix gives the chief new facts up to March 5, 1891. 



The book does not attempt to deal with spectroscopic 

 matters, but occasional references are made, and it is 

 here, if anywhere, that fault may be found. Thus, re- 

 ferring to the nebula of Orion, it is stated (p. 334) that 



"the spectroscopic researches of Huggins have shown 

 this nebula to be composed of incandescent gases, so 

 NO. I I 42, VOL. 44] 



that the stars telescopically observed in it are probably 

 in the foreground and entirely disconnected from the 

 nebulous mass." 



In 1888, however, it was shown by the spectroscope 

 that the stars of the trapezium, at all events, are simply 

 condensations of the matter composing the nebula. 



Everyone who uses a telescope, or who intends to use 

 one, of whatever dimensions, should read Mr. Denning's 

 book. 



OUR BOOK SHELF. 



Abbildungen zur Deutschen Flora H. Kars ten's, nebst den 

 ausldndischen medic inischen Pflansen und Ergdnzung- 

 en fiir das Studiiim der Morphologie und System- 

 kunde. With Woodcuts of 709 Species. (Berlin : 

 Friedlander und Sohn, 1891.) 



This is a wonderfully cheap book, for the price of it is 

 only three marks, and it contains figures with dissections 

 of upwards of 700 plants, illustrating all the natural orders 

 both of Cryptogamic and Phanerogamic plants which 

 make up the European flora or are used medicinally. 

 The text is confined to the preliminary table of the orders 

 and families, an explanation of the details, and a final 

 index. 



The Thallophytae are divided into 17 families, classed 

 under 3 orders, Lichenes being maintained as on a par 

 with Alg;i2 and Fungi. In Cormophytae there are 16 

 families under 6 orders, the orders of Sporiferse being 

 Filices, Selagines, Rhizocarpeas, and Calamariai. In 

 Northocarpae (Gymnosperms) there are 7 families under 

 5 orders, Balanophoraceas and Lorantheae being placed 

 here. Under Teleocarpae (Angiosperms) there are 159 

 faniilies classed under 48 orders, Dicotyledons being 

 divided into Monochlamydeas and Dichlamydeae, and the 

 latter into PetalantheEe (Polypetalae) and Corollanthae 

 (Gamopetalas). The '• families " correspond substantially 

 to Bentham and Hooker's orders. To have such a good 

 and cheap book in English (the text in the original, of 

 course, is German) would be a great boon to students. 



Elementary Text- book of Botany for the Use of Schools. 

 By Edith Aitkin. 248 pp. (London : Longmans, Green, 

 and Co., 1891.) 



This volume has been written to serve as an adjunct to 

 the teaching of Botany in girls' schools, and is the out- 

 come of the author's own experience as a teacher. Miss 

 Aitkin arranges the subject-matter in three parts. In the 

 first are given the general characters of a number of 

 selected types of Flowering plants treated in a manner 

 suitable for young girls beginning the study. In the 

 second part the details of Cryptogamic plants are given, 

 commencing with Protococcus and Yeast, and so on, up 

 to the Fern. In the third part we return to Flowering 

 plants again from a more comprehensive point of view. 

 This last section concludes with a number of chapters on 

 the leading physiological processes of plants. We think 

 the book will be found of service by those for whom it is 

 intended, especially from the fact that Part I. is written, 

 generally speaking, on the lines of the Lower Schedule 

 laid down by the Oxford and Cambridge Schools Exa- 

 mination Board. The only criticism we have to make on 

 this section is that perhaps the style is a little wanting in 

 vitality and interest. Part II. is treated along sufficiently 

 familiar lines, but in Part III., by the introduction of 

 physiological work, with careful instructions as to simple 

 experiments which can easily be performed to illustrate 

 class teaching, we think that the author will have opened 

 up fresh fields of interest in botanical study. The volume 

 is profusely illustrated, many of the figures being new. 



