412 



NATURE 



\_March i, i 



Dynamics and Hydrostatics. By R. H. Pinkerton, B.A. 

 (London : Blackie and Son, 1888.) 



This is a first course of dynamics intended for the use of 

 science classes and colleges, and specially adapted to the 

 requirements of the Science and Art Examinations in 

 theoretical mechanics. The subject is treated mathe- 

 matically, but the mathematical knowledge required for 

 an intelligent perusal of the book is limited to elementary 

 algebra and trigonometry. The fundamental units are 

 thoroughly well explained, and, which is saying a great 

 deal, they are used consistently throughout. Every 

 important proposition is followed by a number of good 

 examples fully worked out, and many others are given as 

 exercises. 



The book is excellently adapted to the Second Stage of 

 the Science and Art Syllabus, and teachers will not have 

 much difficulty in selecting the portions suitable for 

 students working for the First Stage. It is also well 

 adapted for the use of students working at the subject for 

 the London Matriculation and other University Exam- 

 inations. But, notwithstanding these qualifications, it is 

 thoroughly conscientious. In fact, from a mathematical 

 point of view, the book leaves nothing to be desired, 

 lout in this practical generation a greater number of 

 illustrations from every-day life would not have been out 

 of place. A. F. 



Geography for Schools. By Alfred Hughes, M.A. Part 

 I. Practical Geography. (Oxford : At the Clarendon 

 Press, 1887.) 



There are many signs that the study of geography will 

 in future take a much more important place in the or- 

 dinary school course than has hitherto been assigned to 

 it. E\en from the point of view of those severely practical 

 persons who care little about the purely intellectual 

 aspects of education, there can be no doubt as to the 

 value of the kind of geographical knowledge with which 

 this book is chiefly concerned ; and the subject, if 

 properly treated, is one in which young scholars may 

 easily be led to take genuine interest. The present volume 

 will be of great service to schoolmasters who may wish to 

 make a fresh start in geographical teaching. It is based, 

 as Mr. Hughes explains, on the results of seven years' 

 experience in the modern side at the Manchester Grammar 

 School ; and no one who examines the book will be sur- 

 prised that he has found it possible, within the limits of 

 an ordinary term's geographical course, to give instruction 

 on many classes of problems which are not usually treated 

 at school. He begins with the consideration of latitude 

 and longitude, and with rules for the drawing of maps 

 from the atlas and from memory. He then deals with the 

 measurement of the distance between two places on the 

 earth's surface, and explains the rotation of the earth, 

 with the consequent difference in the time of day at two 

 places on the earth. The remaining subjects are the ap- 

 parent movements of the fixed stars ; the Pole star ; 

 Polar distance ; the apparent movements of the sun ; the 

 seasons ; meridian altitude of the sun ; declination ; the 

 length of day and night at any time and place ; the sun's 

 altitude ; place of sunrise and sunset ; the length of 

 twilight ; apparent and Greenwich mean time ; move- 

 ments of the earth ; the length of shadows ; the distance 

 to be seen from mountain summits ; the trade winds ; 

 and the calendar. The questions connected with these 

 subjects are discussed in a way that secures the combina- 

 tion of geography, geometrical drawing, arithmetic, and 

 the elementary ideas of geometry ; and the author's 

 aim is to induce the student to think for himself, 

 rather than to burden his memory with disconnected 

 facts. It is hardly necessary to say how much better this 

 is than .the learning of the names of capes, mountains, 

 rivers, &c., by heart. With such a work in their hands, 

 teachers should be able to make lessons in geography a 



most useful introduction to the study of some important 

 branches of scientific method. 



Key to Todhunter's Dijfferential Calculus. By H. St. J. 

 Hunter, M.A. (London : MacQiillan and Co., 1888.) 



This " Key" will be extremely useful to those who are teach- 

 ing the subject, but more so to those who are getting it up 

 by themselves. The examples are worked out in a clear 

 and intelligible manner, the geometrical problems being so 

 worded that the student can supply figures to enable him 

 more readily to follow the reasoning. To the chapters on 

 " Curve Tracing " and " Miscellaneous Propositions " the 

 author has added figures ; and in the solutions to some ot 

 the examples in chaps, xi., xiii., xv., xx., and xxii., improved 

 methods have been adopted, making the book more useful 

 and complete. Great care seems to have been taken to 

 insure accuracy. 



Electrical Instrument Making for Amateurs. By S. R. 

 Bottone. (London : Whittaker and Co., 1888.) 



In this little book the author has placed before the reader 

 very good and economical methods of making the more 

 useful pieces of electrical apparatus, using only tools of 

 the simplest kind, such as may be found in any house- 

 hold. The instructions are given in a clear and simple 

 manner, and are illustrated by woodcuts, showing the 

 various parts of the apparatus, with the proportions 

 marked on them. Those who are attending courses of 

 lectures on this subject will find this volume immensely 

 useful, as a more thorough and practical insight is obtained 

 by making and using these instruments, however rough, 

 than by mere reading. 



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 

 comm tin ications. 



\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. ^ 



Language == Reason. 



Prof. St. George Mivart has read my letter on " Lan- 

 guage = Reason " in Nature of February 2 (p. 323) with very 

 great care, and I feel grateful to him for several suggestive 

 remarks. But has he read the heavy volume to which that letter 

 refers — my "Science of Thought " ? I doubt it, and have of 

 course no right to expect it, for I know but too well myself how 

 difficult it is for a man who writes books to read any but the most 

 necessary books. I only mention it as an excuse for what might 

 otherwise seem conceited — namely, my answering most of his 

 questions and criticisms by references to my own book. 



Prof. Mivart begins by asking why I should have ex^jlained 

 reasoning by reckoning. 



Now, first of all, from an historical point of view — and this 

 to a man who considers evolution far more firmly established in 

 language than in any other realm of Nature is always the most 

 important — the Latin ratio, from which came raison and our own 

 reason, meant originally reckoning, casting up, calculation, com- 

 putation, long before it came to mean the so-called faculty of the 

 mind which forms the basis of computation and calculation, 

 judgment, understanding and reason. 



Secondly, I began my book on the "Science of Thought" 

 with a quotation from Hobbes, that all our thinking consisted 

 in addition and subtraction, and I claimed the liberty to use the 

 word thinking throughout my own book in the sense of com- 

 bining. Such a definition of thinking may be right or wrong, 

 but provided a word is always used in the sense in which from 

 the beginning it has been defined there can at all events be no 

 misapprehension nor just cause of complaint on the part of the 

 critic ... ^ ^ 



