56o 



NATURE 



[April 29, 1922 



cemed the specimens are not so well displayed as 

 when pinned and set, but,, on the other hand, 

 they are secure against damage, and the " thymo- 

 plas " method should be valuable for teaching pur- 

 poses when specimens must of necessity be handled 

 frequently. Collections mounted in this manner can 

 be stored in microscope slide cabinets with undivided 

 trays. By way of advertisement it is stated that 

 " thymo-plas " is " adopted by Prof. Lefroy as the 

 standard method for use in the Entomological De- 

 partment, Royal College of Science, London." The 

 price of the outfit is 3s. and 6s. according to size. 



Two catalogues of second-hand works of science, 

 each of exceptional interest, have recently reached us, 

 namely, Sotheran's Catalogue of Science and Techno- 

 logy, No. 3, and Heffer's Catalogue (No. 210) of Scientific 

 Books and Publications of Learned Societies. In the 

 former list many works from the libraries of the late 

 Profs. Carey Foster, J. Perry, and P. Duhem are 

 offered for sale. In the latter a prominent feature is sets 

 of scientific journals. The catalogues are obtainable 

 free of charge from their respective publishers — 

 H. Sotheran and Co., 140 Strand, W.C.2, and W. Heffer 

 and Sons, Ltd., Cambridge. 



Our Astronomical Column. 



The April Meteors, 1922. — Mr. W. F. Denning 

 writes that what appears to have been the most 

 brilliant and abundant shower of Lyrids observed 

 during the present century was witnessed by Miss A. 

 Grace Cook and Mr. J. P. M. Prentice, of Stowmarket, 

 on the night following April 21. Miss Cook, watching 

 the sky up to 13 hours G.M.T., observed 30 Lyrids, 

 and a number of others must have escaped observa- 

 tion while the paths of the brighter meteors were 

 being recorded. Eight of the meteors seen were 

 brilliant, six of them being estimated as equivalent 

 to, or surpassing, the lustre of Jupiter. The maxi- 

 mum of the display apparently occurred in the two 

 hours preceding midnight ; the meteors moved 

 swiftly, leaving trails. The brightest object appeared 

 at II h. 12 m. G.M.T., and it left a conspicuous 

 streak which remained visible for twenty seconds. 

 Mr. Prentice also watched the progress of the shower, 

 and saw many briUiant meteors, though the sky w^as 

 partly clouded at times. 



At Bristol the sky was overcast during the whole 

 night, and no meteors could be seen. 



Eccentricity of Double-Star Orbits. — Prof. 

 H. N. Russell shows {Pop. Ast., March) that it is 

 possible to deduce average eccentricities, by statistical 

 methods, even in the case of those long-period systems 

 in which only a very small portion of the orbit has 

 been described. All that is necessary is to note the 

 angle between the tangent and the radius- vector, and 

 compare the observed distribution of angles with 

 that resulting from different assumed values of 

 eccentricity. From observations of 750 pairs he de- 

 duces a mean eccentricity slightly greater than o-6, 

 about the same as that given by stars the orbits of 

 which have been determined. This is an important 

 result from the cosmogonic point of view, as the orbits 

 now considered must be very large, and the periods 

 measured by millenniums. 



Progressive Latitude Changes. — The reported 

 change of the latitude of the International Station 

 at Ukiah, California, at the rate of a foot a year, 

 recently attracted considerable notice. Prof. F. 

 Schlesinger devotes an article to the subject in Astr. 

 Journ., 798. He notes that Cohn's proper motions 

 (depending on the Auwers system) are used for the 

 latitude stars at the International stations, and that 

 they differ systematically from those of Boss. The 

 following list shows the apparent annual change of 

 latitude of the six stations — (i) using Cohn's system' 

 and (2) using Boss's: Mizusawa, Long. -141° (i), 

 -f o-ooo8" (2), -0-0079" ; Tschardjui, Long. -63° (i), 

 +0-0II0" (2), +0-0023*; Carloforte, Long. -8° (i), 

 -fo-0053" (2), -0-0034"; Gaithersburg, Long. +77° 

 (i), +0-0103" (2), +0-00I6"; Cincinnati, Long. +84° 

 (i), +0-0099" (2), +0-0012"; Ukiah, Long. +123° (i), 

 + 0-0106" (2), +0-0019". It will be seen that the 



NO, 2739, VOL. 109] 



systematic northward shift resulting from Cohn's 

 values vanishes when Boss's are used. If we ascribe 

 the changes to a motion of the pole, the indicated 

 motion is 5 inches per annum towards North America. 

 We may, however, consider that at Mizusawa, which 

 is in a volcanic region, there is an actual surface 

 shift of 10 inches per annum southward ; the shifts 

 at the other stations are small enough to be regarded 

 as accidental. Prof. Schlesinger urges that observa- 

 tions at the second, fourth, and fifth stations, which 

 were dropped during the war, should be resumed, at 

 least temporarily. 



Effective Temperatures of Stars. — Various 

 methods used to obtain stellar temperatures give 

 different results, yet it is interesting to note that the 

 divergences are not great ; indeed, for stars of classes 

 G, K, and M, stars of comparatively low tempera- 

 ture, the agreement is fairly close. The cause of 

 these disagreements lies probably in the fact that 

 each observer has limited himself to a portion of the 

 spectrum only, which raay not necessarily contain 

 the observed maximum spectral energy. Dr. W. W. 

 Coblentz, in the Proceedings of the National Academy 

 of Sciences (U.S.A.) (vol. 8, No. 3, p. 49), gives the 

 results of his inquiry into the effective temperatures 

 of 16 stars as estimated from the energy distribution 

 in the complete spectrum. 



By means of screens of red and yellow glass, quartz, 

 and water he found it possible to obtain the radiation 

 intensity in the spectrum in consecutive portions from 

 0-3M to lOjU.. In addition to* an interesting table 

 giving a comparison of the total radiation from stars 

 having closely the same visual magnitude but of very 

 different spectral class. Dr. Coblentz sums up his 

 results in another table, comparing his stellar tem- 

 peratures with values previously obtained by other 

 workers. As the values he has deduced will prove 

 very useful for reference they are here reproduced, 

 commencing with the hottest stars and passing through 

 the various stellar types, taking class Go as standard. 



Temp. 

 13,000° K 

 10,000 

 8,000 

 8,000 

 9,000 

 8,000 

 6,000 

 6,000 

 4,000 

 5.500 

 3.500 

 3.000 

 3.000 

 4,000 

 3.500 

 3,000 



