176 



NA TURE 



[Dec, 22, 1887 



guard some piece of faith as such, then the more wordy 

 our logic the better. And the delight in " naming our 

 tools " may be carried to any length without fear of un- 

 pleasantness. It need commit us to no more than did 

 Mr. Micawber's plan of docketing his unpaid bills. Here, 

 however, it must be left an open question whether the 

 modern practice of ignoring so many carefully-made 

 divisions is an improvement or the reverse. Both views 

 are at least respectable. In any case the elaborate details 

 of the machinery by which our religious creeds are to be 

 kept sacred contain much that ought to be of interest to 

 all. What with criteria per quod and secundum quod 

 (pp. 168, 191), with different " spheres" of truth (pp. 175, 

 202, 203), and different kinds of certainty (pp. 161-68), 

 with truths which are " not intrinsically evident, but 

 nevertheless extrinsically evident, or, rather, evidently 

 credible " (p. 200), one may learn to admire heartily the 

 care and cleverness employed so freely in mediaeval times 

 by those who felt the need of warding off awkward ques- 

 tions. It is certainly no light problem, how logic may be 

 taught without encouraging the dangerous practice of 

 doubting what we are told. 



There are other signs of hard work in this book, 

 besides the patience with which the author has studied 

 the scholastic doctrines. For teaching purposes there is 

 nothing so useful as examples, and here the examples 

 given are numerous, mostly new, and sure to be helpful 

 to the learner. Only those who have tried know the real 

 difficulty of clearly illustrating statements so general as 

 those of logic without some appearance of triviality. In 

 this respect also Mr. Johnstone has succeeded unusually 

 well. Alfred Sidgwick. 



OUR BOOK SHELF. 



Light aftd Heat. By the Rev. F. W. Aveling, M.A. , 

 B.Sc. (London : Relfe Bros., 1887.) 



This is an elementary text-book intended to cover the 

 syllabus of Light and Heat for the London Matriculation 

 Examination. Being written more in the form of notes 

 than as an ordinary book, it will be of considerable service 

 for examination-purposes. Many of the definitions, how- 

 ever, are far from concise, and many phenomena which 

 admit of easy explanation are left unexplained. On p. 98 

 we are told that the specific heats of gases are inversely 

 proportional to the square roots of their densities, 

 whereas they are in inverse proportion to their densities ; 

 had a simple explanation of this relation been given, the 

 mistake would not have occurred. The important subject 

 of thermo-dynamics is disposed of in four pages at the 

 end of the book : this is not as it ought to be, seeing that 

 the relation between heat and work often enters into 

 previous discussions, and is, moreover, the basis of the 

 modern theory of heat. 



The sketches are of a rough-and-ready kind, such as 

 a student would be expected to make in an examination, 

 and, as such, give many useful hints. The coloured plate 

 of spectra, however, is as useless as the majority of 

 similar ones, as practically no explanation of the meaning 

 of a spectrum is given ; dark lines are shown in the 

 spectrum of potassium, but these are no doubt due to a 

 mistake of the lithographer. Such exhibitions as the^e, 

 which are far too common, show a want of respect for 

 the labours of those who have done so much to further 

 our knowledge of spectrum analysis. 



A large number of good numerical problems, with 

 answers, are distributed throughout the text, and several 

 typical ones are fully worked out. A. F. 



Animals from the Life. By H. Leutemann. Edited by 

 Arabella B. Buckley. (London: Stanford, 1887.) 



This work, which forms a charming introduction to the 

 study of zoology, is just the thing for young children who 

 have a turn for the subject, and at the present time, since 

 presents are being made on all sides, would make a very 

 useful and enjoyable gift. From it they will be able to 

 become acquainted with the various forms of living 

 creatures without having to make a laborious study of 

 natural history, which few care to do. A great amount 

 of knowledge can be gained by merely looking at the 

 illustrations, which are got up in a very intelligent and 

 accurate style ; they are 255 in number, and well coloured, 

 and represent animals, including birds, insects, fish, &c., 

 as they are found in their natural state. 



The accounts of the various forms and habits of the 

 different animals (each plate having about a page and a 

 half of letterpress with it), are written so very clearly 

 and in such a natural way that anyone who peruses this 

 book will find plenty that will be extremely interesting. 



In adapting the original text to the wants of English 

 children. Miss Buckley has had to alter it in many places, 

 English examples and references being substituted for 

 German ones. 



The Vegetable Lamb of Tartary. By Henry Lee. (London : 

 Sampson Low, 1887.) 



In former times it was generally believed that there existed 

 in the East a mysterious " plant-animal," variously called 

 " the vegetable lamb of Tartary," " the Scythian lamb," and 

 "the Barometz,"or "Borametz." The usual explanation of 

 this notion is that it originated from certain little lamb- 

 like toy figures constructed by the Chinese from the 

 rhizome and frond-stems of a tree-fern. Mr. Lee, however, 

 holds that the idea came into Europe from Western Asia, 

 and that it referred in the first instance to the cotton-pod. 

 This theory he works out thoroughly in the present little 

 work, and in the course of his argument he has brought 

 together many curious and interesting facts, the signifi- 

 cance of which is made more plain by a number of good 

 illustrations. In a separate chapter Mr. Lee treats of the 

 history of cotton, its uses by ancient races in Asia, Africa, 

 and America, and its gradual introduction among the 

 nations of Europe. 



LETTERS TO THE EDITOR. 



{The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he under- 

 take to return, or to correspond with the writers of, 

 rejected manuscripts. No notice is taken of anonymous 

 communications. 



[The Editor urgently requests correspondents to keep their 

 letters as short as possible. The pressure on his space 

 is so great that it is impossible otherwise to insure the 

 appearance even of communications containing interesting 

 and novel facts. 



The Royal Horticultural Society. 



The affairs of the Royal Horticultural Society alluded to in 

 the last issue of Nature (p. 145) have lately obtruded them- 

 selves upon public attention, but it is probable that some readers 

 of Nature may consider that they have little concern with such 

 a body. They may look on horticulture in the light of a 

 pleasant pastime, or of a more or less profitable commercial 

 enterprise, they may regard flower-shows as a means for the dis 

 play of fashionably-dressed ladies, or they may look on the 

 Royal Horticultural Society as an association for the production 

 and distribution of medals and certificates of more commercial than 

 scientific importance. But there are other considerations beyond 

 these, and whilst naturalists may be indifferent to much of the 

 past history and much of the present work of the Society, to the 

 internal dissensions and to the action of the landlord Commis- 

 sioners towards their unfortunate tenants, the scientific work of the 



