March 29, 191 7J 



NATURE 



93 



therefore hig^hly probable that, as in the case of the 



Ophiuchi nebula described by Slipher (Nature, vol. 



viii., p. 236), the nebula shines by reflected light of 



• • star which it encloses. Other nebulae have also 



L-n investigated, and some of them show feeble 



ices of bright nebular lines in addition to continuous 



>{>ectrum. Very long exf>osures were of necessity given 



in taking the photographs, and it is still uncertain 



what extent the photographed spectrum is influ- 



.ced by light of the associated star which is diffused 



in the earth's atmosphere. 



Imperial Astronomical Society of Russia. — A cor- 

 dial welcome will be extended to the bulletins of the 

 Imperial Astronomical Society of Russia, the first 

 number of which has recently been distributed. It 

 contains a series of notes by M. Viliev, including an 

 hemeris of the planet (67) Asia, a search ephemeris 

 comet 1846 IV. (De Vico), and a note on the pos- 

 ile return of the comet of 1532. In opposition to 

 Mbers, M. Viliev finds reason to believe that the 

 met of 1661 may have been a return of that of 1532, 

 which case its reappearance would be due about the 

 .•sent time ; it remains, however, to make a new 

 luction of the observations made by Hevelius in 

 61, and to calculate the perturbations during the 

 ree revolutions. A further note refers to the central 

 line of the total eclipse of the sun of May 28-29, ^Q^Q- 

 One of the notes is in English, and the remainder in 

 French. 



Monthly Star Maps for 1917. — In response to 

 quests from naval and militan.- officers and others, 

 e annual publication of the Scottish Provident Insti- 

 lion has again taken the form of a star atlas and 

 -tronomical calendar, which has been prepared for 

 ■'i twentieth year in succession by Dr. Blaikie. In 

 idition to the monthly maps, showing the stars in 



■ now familiar gold on dark blue, there is a stereo- 

 : aphic projection intended for the solution of many 



jblems for which the celestial globe is ordinarily 

 nployed. There are the usual tables relating to the 

 ;n. moon, and planets, and these, together with the 



cresting series of explanatory notes, form an admir- 



le popular guide to the heavens. This publication 



is doubtless done much to encourage a general 



terest in observational astronomy, and its usefulness 



this respect might be increased if it were made 



ailable to anyone who was prepared to pay for it. 



riENCE LECTURES TO THE TROOPS 

 IN FRANCE. 



AT the invitation of the War Office, the Young 

 -'■ *- Men's Christian Association recently organised 

 a special service of lecturers to visit suitable centres 

 in France for periods varving from a fortnight to 

 three months or more in order to provide the troops 

 behind the line with recreation of a thoughtful kind. 

 The lectures were arranged because of a desire ex- 

 pressed by many of the troops for occasional entertain- 

 ment of a more solid or instructive character than is 

 offered by moving pictures and concert parties. Their 

 aim has been not merely to afford amusement to the 

 men in their unoccupied hours, but to give an under- 

 anding of the causes and aims for which our troops 

 :- fighting, and to deal with military, naval, and 

 political history, with science, literature, travel, and 

 other subjects of general interest. The scheme has 

 received the hearty support of the universities, the 

 vice-chancellor of each of which has appointed a 

 special committee to nominate lecturers. The details 

 of arrangement have been in the hands of Prof. Gilbert 



NO. 2474, VOL. 99] 



Murray for the War Office Educational Committee and 

 of Mr. Basil Yeaxlee for the Y.M.C.A. 



In connection with this scheme a number of lectures 

 upon scientific subjects have been, and are being, given 

 at base camps and other centres in France. Among 

 the science lecturers who have already completed their 

 courses are Prof. VV. Bateson, Prol. Alex. Findlay, 

 Prof. R. A. Gregorv, Mr. J. Humphrevs, Prof. O. T. 

 Jones, Rev. T. E. 'R. Phillips, Prof. E. B. Poulton, 

 Mr. W. E. Whitehouse, and Dr. F. Womack. Lec- 

 tures have been given to the officers as well as to 

 the men upon such subjects as heredity, chemistr}' of 

 daily life, the sun, moon, planets, and stars, primi- 

 tive astronomy, protective resemblance, war among 

 animals, the life of a river, rocks and soils of northern 

 France, the Great Ice Age, climate and vegetation, 

 mechanical contrivances of plants, and so on. 



The lectures are given in Y.M.C.A. huts, and are 

 usually illustrated with lantern-slides. They have 

 proved remarkably successful, and in most cases the 

 huts have been filled with men who listened with 

 attention and intelligent interest to simple discourses 

 upon natural facts and phenomena and their scientific 

 interpretation. Even when other attractions, such as 

 concerts, moving pictures, and revues have been going 

 on at the same time, large audiences have attended 

 the science lectures, and have thus shown the existence 

 of a real demand for more thoughtful recreation. The 

 welfare work of the Y M.C..A. with the troops abroad 

 is admirable in everv respect, and the scheme of lec- 

 tures now in operation merits all the assistance and 

 encouragement which men of science can give it. 



Although a few separate lectures are given to 

 officers, most of them are delivered to the men, and 

 officers are rarely present at them, though they are 

 attracted by concert parties and like entertainments. 

 It ought not to be supposed that the officers of our 

 Army are less interested in scientific subjects than 

 are the men of the rank and file, and their absence 

 from lectures may be due to the fact that the Y.M.C.A. 

 huts are regarded as places of recreation for the men 

 only. As, however, Mr. McCowen, the chief secre- 

 tary of the Y.M.C.A. in France, reports that the 

 lecture scheme has succeeded almost beyond expecta- 

 tion, it would be worth v.'hile to develop the scheme 

 still further by arranging more lectures few officers, 

 not so much for purposes of instruction as to excite 

 interest in scientific matters. 



Of course, lectures on histor}', literature, the allied 

 countries, and similar subjects have also been 

 delivered, and, on the whole, historical subjects are 

 probably the most popular. There is no doubt, how- 

 ever, that the science lectures have been a source of 

 pleasure and enlightenment to thousands of our troops 

 at the base camps and further up the line, and the 

 Y.M.C.A. is performing a ver\' useful ser\-!ce in 

 organising them. The work is of such decided educa- 

 tional value that it should receive practical support 

 from the State in the form of grants. With so large 

 a part of out population serving with, the forces at 

 home and abroad, it should be possible for the Board 

 of Education to make the Y.M.C.A. an education 

 authority, and pro\nae a substantial part of the funds 

 required to carr\- on and extend the educational enter- 

 prise so successfully begun. 



N ANNA'S CAVE, ISLE OF CALDEY. 



CALDEY ISLAND, in Carmarthen Bay, two miles 

 south of Tenby, has been occupied since the pre- 

 histioric period, and, as is shown by the raised beaches 

 in the vicinity, has been exposed to periodical eleva- 



