Junk 23, 1910] 



NATURE 



48; 



la I ye work, reviewed in this journal on March 3. The 

 ace is regarded as one of harmonising the discrepan- 

 cies that arise through specialisation of chromatic and 

 motor organs in the male, and of assimilative struc- 

 tures in the female. 



In conclusion, we have to regret the absence of an 

 ;.iripx or of a list of references, but we may recommend 

 work as an extremely useful and compact sum- 

 mary of recent work on the physiology of the protozoa. 



AMATEUR ASTRONOMY. 

 An Easy and Concise Guide to the Starry Heavens, 

 arranged as a Companion to the Umbrella Star 

 Map and Revolving Star Dome for Instruction in 

 Astronomy. By D. McEwan. Pp. 137. (London : 

 Kegan Paul, Trench, Triibner and Co., Ltd., 1910.) 

 Price 55. 



THE idea of. using the concave surface of an um- 

 brella as a star map is excellent, but, of course, 

 not new. The portability and convenience of manipula- 

 tion of such a stellar guide are obvious advantages, 

 while the aspect in which the constellations are seen, 

 unlike the view in a celestial globe, corresponds to the 

 reality. The actual construction of such a chart of 

 the sky might quite well form part of the practical 

 work of every elementary course of astronomy. 



A simple guide to the heavens, to be used in con- 

 junction with, and in explanation of, such an adapted 

 umbrella should be worthy of notice. It is to be 

 regretted that the present book, while pretending and 

 seeming at the first glance to fulfil just such a 

 function, cannot be recommended. Somewhat scrappv 

 and not always trustworthy, it gives the impression 

 of being the work of an amateur. 



After a preface and an introduction, chapter i. de- 



- a page and a half to astronomical magnitudes 

 i units, and also describes a chart of the north cir- 

 cumpolar stars, which is reproduced. The stars 

 contained in the various "segments" of the 

 "Umbrella Star Map" are dealt with in chapter ii. 

 The persistently miscalled " segments " are really the 

 K-ctors formed by the ribs and circumference of the 

 umbrella. In the text a certain amount of informa- 

 tion is given about the constellations and the principal 

 stars as they occur in each "segment," while charts 

 "how their relative positions and make a very rough 



mpt to indicate stellar magnitudes. The scheme to 

 . resent magnitude described for the actual umbrella 

 is not in use, apparently, in the companion book. A 

 separate key-map in each case is used to indicate 

 names. A table, giving for each star a serial 

 number, the Greek letter, constellation, magnitude, 

 (Hght ascension, and declination, completes the in- 

 iformation for a typical "segment." General astro- 

 nomical information is introduced relative to special 

 jObjects as they are encountered, so that, without 

 reference to the index, it is difficult to find the treat- 

 ment of any particular subject. 



The information given is often amateurish and 

 sometimes in error, while plausible misstatements 

 which would trouble a beginner are to be found. 

 The solar spectrum, for example, is " well known to 

 -onsist of the seven colours," while by observations 

 NO. 2 12 I, VOL. S;^] 



made through a long tunnel, or from the bottom of 

 a well, " any star coming into the field of view would 

 be seen even in daylight." Under the title • Major 

 Planets " are described Jupiter, Saturn, Uranus, and 

 Neptune, while the " Minor Planets " are Mercur}-, 

 Venus, and Mars. To Jupiter is ascribed only five 

 moons, the date of discovery of the fifth being given. 



Chapter iv. describes a folding key to the 

 " Umbrella Star Map," and the next chapter deals 

 with the solar system in a bald way. In the pages 

 devoted to time, the sun is described as being due 

 east at six o'clock, while amplitude is misdefined in 

 the following chapter. 



A section devoted to scouting and an index to con- 

 stellations bring to a conclusion a book which needs 

 a thorough revision if it is to be of service. 



ELEMENTS OF PHYSICS. 

 (i) .4 First Book of Physics. By Dr. L. Lownds. 

 Pp. vii+145. (London: Macmillan and Co., Ltd., 

 1910.) Price IS. 6c?. 



(2) An Elementary Text-book of Physics. Part IV., 

 Heat. By Dr. R. W. Stewart. Pp. iv + 246. 

 (London : C. Griffin and Co., Ltd., 1910.) Price 

 3s. 6d. net. 



(3) Matriculation Magnetism and Electricity. A 

 Text-book for Use in Schools and Colleges arranged 

 for Modern Methods of Teaching. By Dr. R. H. 

 Jude and J. Satterly. Pp. vii + 415. (Cambridge: 

 University- Tutorial Press, Ltd., 1910.) Price 45. bd. 



(i) HTHIS book is intended for those beginning the 

 -1- studv of physics. The contents do not cover 

 the whole ground usually dealt with, but are confined 

 to the principles of measurement, mechanics, and 

 heat. The reason given for this is that it is now 

 customary in secondary schools to limit the courses 

 of studv to these subjects for the first two years. 

 Students reading this book are expected to be 

 acquainted with the elements of mathematics, and to 

 be able to perform for themselves the numerous ex- 

 periments described in the text. Descriptive and 

 numerical test questions form the conclusion of each 

 chapter. 



There is no doubt it will be found a very useful 

 book. The most pleasing feature is the exactness 

 with which statements are made, at the same time 

 preserving great simplicity of language. Added to 

 this, the printing and diagrams are good, and advan- 

 tageous use is made of heavy type for the more 

 important statements of principles. 



(2) Dr. Stewart's fourth volume is written in much 

 the same style as the three preceding ones. It is suit- 

 able for those possessing no previous exact knowledge 

 of the subject of heat. Attention is paid to all the 

 elementarv thermal phenomena, the order of treat- 

 ment being the usual one. What has been said above 

 in reference to Dr. Lownds's book applies also here. 

 Few difficulties should present themselves to an 

 earnest reader of the subject. Here also many experi- 

 ments are described, but, with the exception of a few 

 worked in the text, examples are absent. 



There is rather a surprising omission, however, in 

 the chapter on the transference of heat by radiation. 



