April 28, 192 1] 



NATURE 



281 



service and the growth of hospitals ; a chair of medi- 

 cine in the fifteenth century ; the rise of the experi- 

 mental method in Oxford; medicine in 1800; medi- 

 cine in the twentieth century ; and Palissy, Bacon, 

 and the revival of natural science. Another work in 

 the list is "A Treatise on Probability," by J. M. 

 Keynes, the author of "The Economic Consequences 

 of the Peace." It will be in five parts on, respectively, 

 fundamental ideas, fundamental theorems, induction 

 and analogy, some philosophical applications of prob- 

 ability, and the foundations of statistical inference. 

 In addition, there will be an extensive bibliography. 

 Messrs. Macmillan will also publish "The Angami 

 Nagas, with some Notes on Neighbouring Tribes," by 

 J. H. Hutton.. It will appear under the direction of 

 the Assam Administration. 



A WORK entitled " Pre-history," by M. C. Burkitt, 

 is announced for publication in the autumn by the 



Cambridge University Press. It will be a study of 

 early cultures in Europe and the Mediterranean basin, 

 and contain a preface by the Abb6 Breuil, with whom 

 the author has collaborated in the study of prehistoric 

 caves in France and Spain. Another autumn pub- 

 lication of the same publishers will be "A Manual 

 of Seismology," by Dr. C. Davison, which will sum- 

 marise present knowledge on the subject. It will 

 be issued in the Cambridge Geological Series. 



Messrs. H. K. Lewis and Co., Ltd., 136 Gower 

 Street, W.C.i, have just published at is. net a Supple- 

 mentary Catalogue for 1918-20 of their medical and 

 scientific circulating library ; also, gratis, their list of 

 new books and new editions added to the library in 

 January to March of the present year. The two 

 catalogues should be in the hands of all who wish 

 to be kept informed of the latest books in medical 

 and general science. 



Our Astronomical Column. 



The Accelerations of the Sun and Moon. — The 

 Journal of the British Astronomical Association for 

 January contains an address by Dr. Harold Jeffreys 

 on this subject. He starts by quoting the results 

 obtained by Dr. J. K. Fotheringham from ancient 

 observations of eclipses and other phenomena (Mon. 

 Not. R.A.S., December, 1920), viz. 21-6" for the 

 moon and 3" for the sun. These are the velocities 

 gained per century per century ; on the less logical 

 system that gives the space gained in a century the 

 figures are halved. Of the lunar figure 12-2" is due 

 to the diminution of eccentricity of the earth's orbii. 

 The remaining 94" for the moon and 3" for the sun 

 are ascribed to tidal friction, which diminishes the 

 earth's rotational speed, thus lengthening the day. It 

 would, at first sight, appear that the effect on the 

 moon should be thirteen times that on the sun, this 

 being the ratio of their mean motions. Since, how- 

 ever, the mutual action of moon and earth does not 

 alter the moment of momentum of the system, a 

 retardation of the earth's rotation is accompanied by a 

 recession of the moon and the consequent lengthening 

 t , of her period, which cancels a considerable part of 

 the apparent acceleration due to the slower rotation. 

 Dr. Jeffreys notes that the theoretical values of solar 

 and lunar accelerations due to tidal friction are un- 

 certain, and may be anywhere between i to 3 and 

 I to 10. He then describes in detail the recent work 

 of Major G. I. Taylor and himself (already described 

 in this column) which determined the regions on the 

 earth's surface where the friction is taking place; the 

 Bering Sea is the largest contributor, but the action 

 in the Irish Sea is quite sensible. 



1646 Spectroscopic Parallaxes. — The Astrophysical 

 Journal for January last contains an important list of 

 1646 spectroscopic parallaxes by W. S. Adams, A. H. 

 Joy, G. Stromberg, and Cora G. Burwell. The paper 

 commences with a re-discussion of the spectral gradua- 

 tion tables in the light of the extensive series of 

 trigonometrical parallaxes recently published, especially 

 those at the Allegheny, McCormick, Yerkes, and Mount 

 Wilson observatories. In the case of the Cepheid 

 variables and giant M stars use has also been made 

 of the parallactic motions, since these stars are, in 

 the main, too remote to lay much stress on their 

 trigonometrical parallaxes. 



The new list includes revised values for 495 of the 

 stars in the 19 17 list. It is satisfactory that many 

 A stars are now included in the list, which formerly 



NO. 2687, VOL. 107] 



did not extend beyond F. A few of the larger or 

 more interesting results are quoted below, marked S, 

 the trigonometrical results (T) being given for com- 

 parison : 



OAN 4961, P.M. 053", S o-ioo", no T; Aldebaran, 

 S 0096", T 0055"; Capella, S 0076", T 0067"; Betel- 

 geux, S 0-012", T 0021"; Castor (faint distant com- 

 panion), S 0091", T 0079"; Pollux, S 0-126", T 0064" ; 

 Boss 2199, S o-iio", T 0081"; Regulus (companion), 

 S 0-052", T 0033"; Boss 3047, S 0-105", T 0235" (only 

 one determination); Arcturus, S 0158", T 0-075"; 

 y Serpentis, S 0120", T 0063"; Antares, S 0-017", 

 T 0-029"; A Sagittarii, S 0115'', T 0069"; ^3' Cygni, 

 S 0033", T 0-000"; ^ Aquilae, S 0100", T 0076"; and 

 Boss 5976, S 0-209", T 0-172". 



For the f>eculiar variable or nova 7 : 19 17 Serpentis 

 the value of S is 0003", the absolute magnitude being 



2-9. 



Several large parallaxes havi not been quoted, 

 since they are practically replicas of the accepted 

 values. 



A Catalogue of Radial Velocities. — Many workers 

 in stellar statistics must have felt the inconvenience of 

 having to ransack the publications of several ob- 

 servatories in order to obtain complete details of 

 known radial velocities. The need for a catalogue has 

 at last been supplied by Mr. J. Voiite, who was for 

 some time at the Cape Observatory determining 

 stellar parallaxes. While he does not claim that his 

 catalogue is absolutely complete, it includes all the 

 stars, 2071 in number, for which radial velocities were 

 g-iven ir# publications that were accessible in the 

 library of the Cape Observatory. It is arranged in 

 a convenient form, giving R.A. and declination for 

 1900, magnitude, proper motion, spectral type, radial 

 velocity, parallax, and galactic longitude and latitude. 



The numbers of stars of each spectral type are : — 

 Oe 6, B 310, A 358, F 257, G 309, K 517, M 153, 

 R II, and nebulag and clusters 148. The largest + 

 and — radial velocities for each type in km. /sec. 

 are: — B, +102, —38; A, +96, —170; F, +339, —325; 

 G, +301, -242; K, +177, —132; and M, -f-98, —185. 

 There appears to be a distinct maximum for tvpes 

 F and G, 



The work was published at Weltevreden, Java, by 

 Boekhandel, Visser, and Co. 



A statistical study of the results by Prof. George 

 Forbes was presented at the March meeting of the 

 Roval Astronomical Societv. 



