98 



NATURE 



[September 15, 192 1 



frequent in the case of cathode or /3-rays in air sup- 

 ports his view. 



A FURTHER contribution to the study of the African 

 rift valleys and their world-relations will be issued 

 shortly by Messrs. Seeley Service and Co., Ltd., in a 

 new work by Prof. J. W. Gregory, entitled "The 

 Geology and Rift Valleys of East Africa." Its object 

 is to show the continuity of the rift valley from Pales- 

 tine to south of the Zambesi, with the exception of 

 a short gap in the southern part of the Tanganyika 

 territory. The work also summarises the volcanic 

 history of East Africa, and shows that the rift valleys 

 have been formed by a series of earth movements 

 connected with the foundering of the Indian Ocean. 

 These movements began in the Cretaceous, and have 

 lasted until quite recent times. Some movements in 

 connection with them are probably still in progress. 



The new list of forthcoming books just issued by 

 Messrs. Methuen and Co., Ltd., contains a number 

 of works relating to the subject of relativity, viz. : — 

 " Space— Time— Matter, " Prof. H. Weyl, translated 

 by H. L. Brose; "Einstein the Searcher: His Work 

 Explained from Dialogues with Einstein," A. Mosz- 

 kowski, translated by H. L. Brose; "An Introduction 

 to the Theory of Relativity," L. Bolton; "Relativity 

 and the Universe," Dr. H. Schmidt, translated by 

 Dr. K. Wichmann ; "The Ideas of Einstein's 

 Theory," Prof. J. H. Thirring ; "Relativity and 

 Gravitation," by various writers, edited by J. M. 

 Bird; and "The Fourth Dimension Simply Ex- 

 plained," a collection of essays selected from those 

 submitted in the Scientific American's prize contest, 

 with an introduction and editorial notes by Prof. 

 H. P. Manning. 



Our Astronomical Column. 



The Bright Object op August 7. — Astr. Nach. 

 No. 51 18 contains a further observation of this object 

 made at Plauen, Vogtland, by the daughter of Prof. 

 E. Kaiser and several others. It appeared like Venus 

 at its greatest brilliancy, low in the evening sky 

 shortly after sunset. Its position with regard to dis- 

 tant terrestrial objects was accurately noted. At 

 G.M.T. yh. 35m. its azimuth was 98° 226' from south 

 to west, and its apparent altitude 2° 359'; or 2° 21-9' 

 corrected for refraction. Plauen is in N. lat. 

 50° 29' 45", long. E. Greenwich 12° 7' 11"; Prof. M. 

 Wolf deduces that the R.A. of the body was 

 iih. 67m., N. decl. 7° 9'. This gives longitude 

 1650°, N. lat. 1° 20'. It may be mentioned that the 

 place of Jupiter was R.A. iih. 23-9 m., N. decl. 5° 6', 

 but it does not seem possible that this could have 

 been the body observed. 



The Lick Observatory position at G.M:T. i5h. was 

 about R.A. gh. 22m.,' N. decl. 158°, or longitude 

 138°, N. lat. o-4°. 



■It is to be noted that the object observed in Eng- 

 land was much closer to the Sun (estimates of dis- 

 tance 6° and 4° respectively) than the Plauen object, 

 so that an element of doubt remains. But the latter 

 observation was made in a much more exact manner, 

 so it deserves greater weight. If we assume the iden- 

 tity of the Plauen and Lick objects, _ and that the 

 motion was parabolic, then the maximum distance 

 from the earth on August 7 was 0-005 in astronomical 

 units, or about twice the moon's distance. It appears 

 unlikelv that a comet at this small distance would 

 "have such a well-defined stellar appearance. 



Einstein's Real Achievement. — The Fortnightly 

 Review for September contains an article with the 

 above title bv Sir Oliver Lodge, in which he alludes 

 to the awakening of interest in relativity brought 

 about bv Einstein's visit to England and the publica- 

 tion of Lprd Haldane's book, which extends the doc- 

 trine to a wider field than that of kinematics. 



Sir Oliver Lodge notes that the more ardent rela- 

 tivists treat the subject from a purely geometrical 

 point of view, and endeavour to eliminate all refer- 

 ence to phvsical laws. For example, they suggest 

 that the speed of a falling apple may be equally well 

 attributed to the earth, and that the diurnal rotational 

 movement mav be ascribed to the heavenly bodies 

 themselves. Thev minimise their references to the 

 eether, some of them denying its existence. He depre- 

 cates these methods of treatment as unlikely to lead 

 to advance in our knowledge of the universe. For 

 his own part he expresses an ardent belief in _ the 

 realitv of the aether and its association with electricity • 



NO. 2707, VOL. 108] 



and matter. He gives a brief risunii of the work of 

 Clerk Maxwell (extended by Larmor, Lorentz, and 

 Thomson), referring in particular to the relation con- 

 necting the electrostatic and electromagnetic units 

 with the velocity of light, and passing on to the 

 Lorentz-FitzGerald contraction, which plays an im- 

 portant part in the equations of relativit}-. 



He urges the retention of the Newtonian conception 

 of force in celestial mechanics, the simple law of in- 

 verse squares being amplified by the addition of the 

 terms arising from the change of inertia with motion. 

 He expresses his admiration at the skill which has 

 succeeded in reducing the action of forces to formulae 

 in pure geometry ; nevertheless, he considers that one 

 is thereby introducing complexity and departing from 

 the realities of Nature. However, throughout the 

 article there is nothing but praise for Einstein's 

 achievements, and criticism is merely directed against 

 the method of expressing them. 



Nebular Lines in Spectrum of R AguARii.^The 

 detection of the bright . nebular lines at 4363, 4471 

 (helium), 4658, 4959, and 5007 superposed on the Md 

 spectrum of this star was announced in 1919 by Mr. 

 Paul Merrill, who gives an account in the Astrophys. 

 Joiirn. for June of his further researches on the spec- 

 trum. Four spectra are reproduced, three of which 

 were taken about a month before maximum (magni- 

 tude 8-^ to 70), and the fourth forty-seven days after 

 minimum (magnitude 102). The first three show a 

 continuous spectrum with the customary lines and 

 bands of the Md type, together with the five bright 

 lines. The fourth' shows the bright lines quite as 

 strongly as at maximum, but there is no trace in the 

 reproduction of a continuous spectrum, and it is noted 

 that it was practically absent even with considerably 

 longer exposures. 



There is also a comparison of the displacements of 

 the two spectra on the plates taken near maximum. 

 The Md bright lines give -33 km. /sec, Md absorp- 

 tion lines -19, nebular lines except 4363 -10, and 

 4363 nebular -25. A statistical investigation on 

 the stars of Md spectrum is being undertaken in the 

 hope of determining whether the bright lines or the 

 absorption ones, or neither, give the correct radial 

 velocitv. Many of them, including Mira Ceti, give 

 the same relative displacement of about 14 km. /sec. 



Mr. Merrill suspects that the appearance of the 

 nebular lines in the spectrum of R Aquarii may have 

 taken place quite recently. He has examined the 

 Harvard objective-prism spectrograms (dating from 

 1893). These lines are not observable on them. 



