454 



NATURE 



[September 22, 1923 



: the correct value had been pubHshed 



liii tv years earlit-r by Kit liiird N'orwood. 

 f;t( t that intfriiatioi) il jc.ili ived the 



■'■ •' '■ ..!<!. ''wof^ut^. •■•• "ferns 



however, - cho 



' '■ III some 



• article 

 ! i..it \ •)!'. uru played in 

 ili( until ol Newton's law. 

 iMul that bcluiu the return of Halley's comet 

 ( liir.uit and Lalande calculated its perturba- 



tcst 

 in I 

 'Jhe 



01 ! 



quai 



shows the iiupui 



persnadinK the I'l 



Tlui 



111 I , 



tioiis liv •;! i\ i! ; ional methods. Prof . Forsyth makes 



thr pr.uih.ii ii^gestion that the bicentenary of 



Ni \\ton . <li,iih in 1927 should be markrl l.\ a new 



o(hti()n ot ins collected works. There has been none 



since Horsley's edition in 1785, ai 

 manuscripts have been discovered since m . 



T-^ ^' ''- "- - •- - -- --—,.,, „v ,„ 



E; ,n to tl. 



usual sian mo!i. a ^(>oa deal of matt* 



of scientih I here are chapters on t!: 



geographical features, and special attcir 

 the Nile. Agriculture and antiquities r( 

 able attention, and there is a long section on irrig.. 

 It is noted that the almanac is intended to b 

 planatory and descriptive rather than statistical, a 



thi^ T'-' ♦ ;- '•'■> ied to supplement the " Ant, 



St l)Ook is a valuable volun 



reterence on hgypt. 



Our Astronomical Column. 



A Lak .1 1 iiiBALL. — Mr. W. F. Denning writes: 

 " On Sepicniber 7, at 7.45 p.m., G.M.T., a large fireball 

 was observed from many places in the south-west of 

 England. As viewed from Pnr, Cornwall, it appeared 

 as large as the full moon, and passed from the west 

 over north-west, and luially disappeared in north- 

 north-west. It left a brilliant trail of light, and this 

 remained conspicuously obvious to the imaided eye 

 (Inrini; lixc ininults. The trail exhibited some 

 singular changes oi shape and position while it con- 

 tinued in sight. It first assumed a vertical direction, 

 after which the extremities curved to the left and 

 formed a semi-circle. 



" A number of other observers in Cornwall have 

 reported observations of the phenomenon, and among 

 other places it appears to have been well observed 

 at Fowey, Liskeard, and Polruan. ihe object was 

 also seen from Southampton, from which place the 

 enduring streak was situated due west at an altitude 

 of i6°." 



Stellar Masses. — Accumulating statistics on 

 binary systems, combined with the great increase in 

 the number of fairly trustworthy parallaxes, have 

 made it possible to deduc^pif an .values of the stellar 

 masses for each spectraT type. Messrs. Russell, 

 Adams, and Joy investigate the matter in a joint 

 paper in Pub. Ast. Soc. Pacific for August, using 

 about 400 stars. They assign to type O masses of 

 6 to 9, to type B niass 6, to giants of types A to G 

 masses 2 to 4, and to the dwarfs of all classes masses 

 ^ to 2^ ; in each case the unit is the sun's mass. 



On plotting mass against absolute magnitude, they 

 obtain a graph that is practically a straight line, 

 though with a slight upward bend for type B. This 

 result seems to lead to a fairly obvious corollary, 

 which is not, however, given by the authors. It is 

 that the duration of the stellar universe in the past 

 is of the same order as that of the luminous period 

 of individual stars. If it were much greater than this, 

 then even the most massive stars would have had 

 time to distribute themselves among all the ranks of 

 absolute magnitude. The same conclusion is obtained 

 by dynamical studies of the stellar motions, which do 

 not indicate any great preponderance of non-luminous 

 stars. 



The recently published report of the Cape Observa- 

 tory states that the stellar masses are also being 

 investigated there. The results suggest that the 

 masses group themselves about certain standard 

 values, 11^, 5J, 2|, I J of the sun, each being about 

 double the following. If this law should be estab- 

 lished, it would indicate that the large masses were 



NO. 2812, VOL. 112] 



determined by some jIivm a! 1 

 were liable to successive subd I 



Heat Radiations of I'l....,, ■ , .»■■., -■..,, iui^ 

 already been madt in these notes to the investigation 

 by Messrs. Edison i'.-nit and Seth Ni<fi'>l-"" -"^ »i.'- 

 dark heat-waves emr he plan< 



isolated by the use over-glas^ :„ ,..._ 



between 03 m and 5-5 n (with a weak extension t' 

 75 fj.), and a water-cell transmitting between 03 . 

 and 1-3 M. The curve of atmospheric transmission a: 

 Mt. Wilson is a very complicated one, with eight minima, 

 between o and 8 m, and xima between 8 . 



and 14 M. The dark pla: liations are chieflv 



in the latter region. Ida vlcllcxion from the planet 

 Mercury has been comjiared with that from the moon 

 the ratio of : " i jur unit area being 264'j 



smaller r. ; i vonld Iv expected in vie 



Mercury's proxn my to the sun. The authors ; 

 the sn<4L;estion that it may indicate a rapid rot 

 of Mercury ; they note in corroboration of this uiat 

 they obtain a sensible deflexion even from the dark 

 portion of Mercury's disc. 



Their former measvires indicated practically no dark 

 heat from Jupit.'^ '.i; ti,, present series gives 781 

 per cent, of its ween 0-3 m and 13 >;, 



15-3 per cent, be: 1 , and 5-5 1*. and 60 per 



cent, between 8 fi and 14 m. 



A Small Stellar Mass. — Astr. Xachr., No. 5246, 

 contains an investigation of the orbit of the binarv 

 O. Struve 400, by P. Meier. The position for 1900 

 is R.A. 20^ 6"' 54 , X. I )ecl. 43° 39', magnitude 7-7, 

 spectral type G 3 ; trigonometrical parallax 0043' 

 (Sproul Observatory), spectroscopic parallax 0-030' 

 (\It. Wilson). The elements obtained are: period 

 84-4 years, periastron 1885-1, e 0-48, u> 19-4°, 12 143-9', 

 i 62'5°, a 0-428". The observations used extend from 

 1843 to 1922, so that practically a revolution has been 

 completed. Using the Sproul parallax, the sum of the 

 masses is 0-138 of the sun. (By a slip this is printed 

 in Astr. Nachr. as 0-014 of ^^^ sun.) 



The smallest stellar mass hitherto measured is that 

 of the faint component of Kriiger 60, which is about 

 one-seventh of the sun ; but if the present result is 

 trustworthy, the joint mass of the pair is equal to 

 that of this star. 



A comparison of observed and computed positions 

 is given. The agreement is fair, considering the 

 closeness of the pair. The star is one that should be 

 kept under observation. The components are fur- 

 thest apart, 0-62', in 1932 ; the separation is more 

 than 0-50' till 1948. 



