512 



NATURE 



LJUiNE 15, lyii 



an arbitrary space curve being given, it can be con- 

 sidered as one branch of the flecnode curve of an 

 infinity of ruled surfaces, into the general expression 

 of which there enters an arbitrary function. On the 

 other hand, two curves taken at random cannot be 

 connected, point to point, so as to be the complete 

 flecnode curve on the rulfd surface thus generated. 

 •As the author remarks, tluTi- is no doubt that the field 

 thus onened promises valuahl- results. So far as the 

 analysis goes, it follows the lines of the known theory 

 of differential invariants, constructed by Halphen, Lie, 

 and others. 



Finallv, Prof. Mason j^ives an interesting summary 

 of various boundary-value problems of differential 

 equations. Perhaps one of the most elegant things 

 in this essay is the construction of a doubly periodic 

 Green's function G, which satisfies the equation 

 Ah = o within the period rectangle, except at two points 

 where it is logarithmically discontinuous. This is fol- 

 lowed by a remarkable a^'^lication to the equation 

 Au = f{x, y), where / is periodic in x, y independently, 

 with periods a, b equal to the leng'ths of the sides of 

 the period rectangle of G. 



It is noteworthy to find the United States maintain- 

 ing so many distinguished mathematicians, both 

 native, and, if we may be excused the term, imported. 

 When will the English nation wake up to the fact 

 that it is not waste of money, or at best a concession 

 to dilettante ideals, to provide a living for a first-rate 

 mathematician, even if he proposes to devote his life to 

 varieties in n dimensions, or the theory of aggregates, 

 or the distribution of primes? Surely, and at an 

 accelerating rate, the dominion over nature and over 

 their fellow-men is coming into the hands of the star- 

 gazers, the speculators, the originals, who have been 

 lampooned and pilloried from the age of Aristophanes 

 to that of Swift, and from his days to our own. Or 

 rather, the material profit, the worldly dominion, w-ill 

 come to those nations that have the sense to see that 

 by attracting these creators of new ideas they are 

 encouraging every kind of higher invention, and buy- 

 ing in the cheapest market the best of goods — brains. 



G. B. M. 



IMPRESSIONIST ASTRONOMY. 

 The Night-Skies of a Year : Being the Journal of a 

 Star-gazer. By J. H. Elgie. Pp. xii + 247. (Lon- 

 don and Leeds : Chorley and Pickersgill, Ltd., 

 1910.) Price 65. net. 

 '"FLAKING sections for each month of the year as 

 J- basis, the varying aspects of the constellations 

 are presented in a series of discursive notes purport- 

 ing to describe the impressions of the writer on the 

 occasions when he observed the various objects. 

 The author takes as his aim the task of teaching 

 the geography of the sky by means of a journal show- 

 ing how the constellations alter in their relative 

 aspects from night to night, and at different times 

 on any night. So far this is commendable. It is 

 evident, however, that the desire to produce a volume 

 of impressive magnitude has induced the decision to 

 inflict a superfluity of purely personal impressions ; 

 if these were in the main likely to be experienced by 



NO. 2172, VOL. 86] 



other observers, they might be helpful, but from the 

 nature of many of them it is very questionable if tlu v 

 can be. Take as an example the following:-- 



"Ten o'clock! Ugh! How drear and dismal i-. 

 the night, a night unrelieved by star or moon. Kaiii 

 is beginning to fall. The tempting gleam of a 

 brightly burning fire comes out to me through my 

 window, so I will indoors and try to think that this 

 really is the opening of the ' merrie month.' Then, 

 to round off the evening presently, I will study anew 

 an appropriate article on the old, old question of ' Is 

 the climate changing?' If matters do not mend 

 soon I shall alter my opinion on that subject and 

 persist that the climate is changing." 



This quotation is a fair sample of the style of the 

 whole, though here and there one finds an oasis of 



more acceptable material. • ;•? 



The book is illustrated by numerous rough sketches 

 of constellation groups, and if these were not specially 

 intended for instruction they might be passed over. 

 The author specially directs attention to these sketches, 

 and says : — 



" I am convinced from the letters of numerous 

 correspondents that the difficulty of recognising tht 

 main outlines of the constellations at any hour from 

 the charts accessible to them has damped the enthu- 

 siasm of thousands of beginners in the study of 

 astronomy." 



Our opinion is, however, that the star alignment 

 diagrams are perhaps the most unsatisfactory feature 

 of the book. Taking any one constellation, even 

 such a well-known one as Orion, for instance, it is 

 shown with the component stars, in different relative 

 grouping on consecutive pages, due, it must be 

 assumed, to defective drawing. We would advise the 

 "numerous correspondents" to purchase a trustworthy 

 star atlas, and endeavour to commandeer the help of 

 a capable friend for about five minutes each week. 

 This would do away with all the damping of their 

 enthusiasm. 



SNAKES OF CEYLON. 

 The Snakes of CeyJon. By A. F. Abercromby. Pp. 

 vi + 89. (London: Murrav and Co., 180 Brompton 

 Road, S.W., 1910.) Price 25. 6d. net. 



THE author, being of opinion that the " many works 

 and treatises " in which the snakes of Ceylon are 

 described are "more suited to the scientist than the 

 naturalist," and that "natural historj- books., on the 

 other hand, seldom give sufficiently detailed informa- 

 tion about snakes," has produced a volume which 

 the discerning reader will see at once to be not in the 

 roll of common art. The systematic part being an 

 admitted compilation from well-known works on the 

 fauna of India, we may restrict our inspection to 

 those parts of the book which reveal the originality 

 of the writer. 



In dealing with the anatomy and physiology of 

 snakes, the author laments that " the effect of, and 

 antidotes for, snake poison is a subject which has 

 been much written about and much discussed, but 

 very little has been discovered about it." He has 

 heard of permanganate of potash at least, but this, 

 "although a very successful absorbent remedy, is 



s 



