July, 1905] 



KNOWLEDGE & SCIENTIFIC NEWS. 



155 



upon as reliable and unbiassed. We are frequently having 

 foisted upon us guide books of " How to take out a Patent," 

 which prove to be nothing more than the advertisement of 

 some enterprising firm of patent agents, and such works, 

 though frequently quite correct, one is bound to regard with 

 a certain amount of suspicion. 



Electro-magnetic Theory of Light, by C. E. Curry, Ph.D. 

 Parti.; pp. \i. + 400. (London: Macmillan ; 12s. net.) — 

 This is one of those books of which we would speak nothing 

 but good if we could. It has evidently been laboriously com- 

 piled, and the whole ground has been covered of that portion 

 of the theory which was developed by Maxwell himself. More 

 modern developments which must includesuch matters as dis- 

 persion, which was left unexplained by Maxwell in his Treatise 

 [but which were niuhi'stood by him as is shown by an examina- 

 tion question set by him — as pointed out by Lord Rayleigh] , 

 have been relegated to a second part. Each section is fol- 

 lowed by a large number of examples, very many of which have 

 been excellently chosen. Since these are often worked out in 

 detail they form an excellent means for a student to familiarise 

 himself with the subject. When we have said this, however, 

 any praise of a fairly enthusiastic kind is at an end. The 

 style in which the book is written is not good ; indeed it is re- 

 pellent. We have pored over many paragraphs without being 

 able to obtain their meaning. Special points which seem to 

 be peculiar to the author displease us most of all. We do not 

 like his use of the phrases primary and secondary waves in a 

 sense distinct from that in which they are already used — viz., 

 in connection with Hugyen's theorem.. Still less do we approve 

 of the whole page devoted to a fanciful analogy to primary and 

 secondary currents by which an attempt is made to justify the 

 new use to which he puts these phrases. Simple methods of 

 proof of theories which are familiar to us are replaced by 

 elaborate and confusedly stated methods without any gain in 

 accuracy. On the whole we have said enough to indicate our 

 opinion ; and conclude by stating that the publishers have 

 done their part in a most excellent manner. 



The Norwegian North Polar Expedition, 1893-6. Edited by 

 Fndtjof Nansen. Vol. VI. (Longmans, Green and Co.; 

 price 56s. net.) This great volume deals with the meteoro- 

 logical results of the expedition, and is the work of Professor 

 H. Mohn, who planned the meteorological work to be con- 

 ducted, and superintended the equipment sent with the Frain. 

 Such a great work, conducted with skill and care, forms an 

 important addition to scientific literature. The observations, 

 continued through three years of travel in regions hitherto 

 unknown, were mostly conducted by Captain S. Scott Hansen, 

 who had received special instruction in this subject from Pro- 

 fessor Mohn. The book is[maiuly divided into three portions; 

 the first describing the instruments and observations; the 

 second, the actual diary tables of observations ; and the third 

 the results worked out. The observations were made every 

 four hours, and show the direction and velocity of the wind, 

 the barometric pressure, the temperature, the vapour-tension, 

 relative humidity, and clouds. As regards the direction of the 

 wind, which, by the way, has an important bearing on the 

 probabilities regarding the fate of the Andree expedition, a 

 cursory glance would lead one to suppose that the various 

 winds were fairly equally prevalent, some predominating at 

 certain seasons. The value of this collection of observations 

 is the more evident seeing that they extend over three years, 

 for otherwise one might be led into supposing that certain 

 winds predominated during certain months; but the records 

 of other years seem, in most cases, to prohibit any such con- 

 clusion. In July, the month during which Andree started in 

 his balloon, the prevailing winds were — 1894, W.N.W. and W. ; 

 i8y5, W. and W.S.W. ; 1896, S.W. and S.S.W. As regards 

 the velocity of the wind, the monthly means vary from about 

 three to five metres per second. The velocity, as may be 

 expected, was on the average greater during cloudy weather 

 than with a clear sky. The maximum velocity recorded was 

 only 18 metres per second, and the occasions were very rare 

 when this figure was approached, so that anything approach- 

 ing a real storm was rare. The barometric pressures call for 

 no comment, varying as a rule between 740 and 780 mm., 

 but when we come to temperatures we find some unusual 

 figures. The coldest month was apparently March, with a 

 mean of —37^^ C. the mminnim recorded being —52°. In July 

 and August we occasionally find a mean daily temperature 



just above freezing point. At the end of the book are a 

 number of charts and diagrams. 



Ambidexterity, or Two- Handedness and Two-I5rainedness. By 



John Jackson (Kegan Paul). This is a large book to devote to 

 so little-studied a subject, and we hope it may be the means of 

 bringing forward the importance of that most useful accom- 

 plishment of being able to use both hands, or perhaps we 

 should say either hand, for all ordinary purposes. To be able 

 to write two letters simultaneously, or to draw two different 

 pictures at the same time, is certainly an extraordinary feat of 

 dexterity, but is now described as being easily learnt. One 

 hand at a time is, however, sufficient for most people to em- 

 ploy, and it is certainly desirable to acquire the knack of 

 using the left hand for writing and other purposes. 



A Catalogue of Zodiacs and Planispheres, by the Rev. A. P. 



Grimaldi, M.A. (Gall and Inglis), is a most useful compilation 

 describing the various records from the earliest times of 

 zodiacs in all countries. The number of entries is 1,444. 

 Some of them are a little vague, as, for instance, No. 148, 

 which reads: " A Chinese zodiac is mentioned by Pettigrew," 

 and but few of them have the date or supposed age of the record. 

 Nevertheless, the list should prove of great value to all inte- 

 rested in this subject. 



Petrol Motors Simply Explained. By T. H. Hawley (Percival 

 Marshall; price, is. net). This is one of those useful little 

 manuals intended to instil into the mind of the Man in the 

 Street some knowledge of the working of the machine that 

 carries him about. In the preface the author explains that 

 "the object aimed at is rather a simple explanation of the 

 principles governing the action of the petrol motor, and the 

 manner in which the power so generated is utilized to propel 

 the vehicle, together with a few hints on control mechanism 

 and driving." 



Notes and Questions in Physics. John S. Shearer, Ph.D. 

 (Pp. vii. + 281. New York: The Macmillan Company; 

 London: Macmillan and Co. ; price 7s.6d.net). — The object 

 of this volume is to provide a collection of examples in physics 

 with a sufficient number worked out to suggest methods in 

 typical cases. The fact that students continually complain of 

 their inability to solve .simple problems in physics is a clear 

 indication that the fundamental principles are not fully 

 grasped ; and it is essential therefore to supplement lecture 

 and laboratory work by a reasonable amount of problem 

 work. It is in this way only that a student learns whether he 

 has really understood a principle. The greater number of 

 the problems selected here can be worked by simple algebra 

 or arithmetic ; though in a few cases the calculus is necessary. 

 It is obviously intended that the book should be used with the 

 assistance of a teacher, since answers are not given ; the 

 private student is hereby put at a disadvantage, for he has no 

 test as to the accuracy of his work. There is surely very 

 little objection to including the answers in any book of colle- 

 giate standing, whatever method may be found best for a 

 school book. If a student who has come to years of discretion 

 thinks right to merely " crib " the answer he reaps his reward. 

 Such a man will prove of little use in this world, at any rate. 

 The problemsare judiciously chosen, so that both the academic 

 and the technical student is catered for. We notice a few 

 mistakes. There are unfortunately some in the tables at the 

 end. When are text-book writers going to realize that the 

 fundamental standards of mass and length are no longer the 

 old ones " kept in the Archives at Paris." Is the work of the 

 International Bureau a small thing that it should be so 

 ignored ? 



Elementary Microscopy. By F. Shillington Scales, F.R.M.S. 

 (Bailliere, Tindall, and Cox; price 3s.) A handbook for begin- 

 ners, which is thoroughly practical, concise, and explanatory. 

 With so many modern improvements of detail, most of the 

 larger handbooks on the microscope are becoming out of 

 date, and they are, moreover, as a rule, slightly beyond the 

 requirements of the mere beginner, who wants toknow in as 

 few words as possible what sort of instrument to purchase 

 and how to use it. " Nature, as revealed by the microscope, is 

 quite outside the scope of this little book," which is very 

 properly confined to descriptions of the instrument and its 

 accessories, with hints on its manipulation, and methods of 

 mounting objects for inspection. There are 78 good, clear 



