74 



NATUKL 



September 26, 1918 



OUR ASTRONOMICAL COLUMN. 



; II M 1; I imi l\ 1 ill \r \ll Army 



Order i : iveek states thai from Oclob thi 



1 Hi -foui -hour time 1 1 1 koning, starl mg 



lit, will be adapted throughout thi 1 I tish 



Army. l"h - system is .drench in general use al seaj 



1 1 ope thai its introduction into the Army is 



owards its adoption In the general public. 



3 were made in this direction thirty years ago; 



Sii VV. Christie had the gate-clock at Greenwich 



arranged to show this time, and ii was suggested 



thai astronomers should change the cammencemeii 



ol their da} from noon to midnight, so as to have a 



single system for all purposes. Both proposals ccs 



lapsed ai thai time owing to insufficient driving-poweHj 



Inn thej an- now being revived with better prospects 



el success. There is .1 great probability thai the 



various astronomical ephemerides will from the yean 



[925 use Hi. da\ commencing at midnight; the neces* 



viu' of preparing thi si ephemerides many years in 



advance maki an earliei change impracticable. But 



there is no reason why the general use ol twentjt 



four-hour reckoning should not begin sooner. II aw 



railwa; 1 impanies could !»' induced to use it in their 



time-tables it would prevent all confusion between 



a.m. and p.m., and would also accustom tin- public 



1,, the system. The Army Order stales that four 



figures are always to be used for hours and minutes; 



ample, 4.7 a.m. will he written as 0407. This 



is a convention already familiar to American 



astronomers. 



Wolf's Comet. The following ephemeris foi Green, 

 wich midnight is In M. Kamerista (AStr. Jcnm., 



No. 73 8) : 



Date R.A. N. Dec]. Log »• Log 2. 



Oct. 



I 20 12 33 



5 JO 17 o 



i) 20 -'2 6 



13 20 27 51 



17 20 ;4 to 



2 1 JO 41 S 



25 20 4 s 35 



29 -'" 5° 34 



11 46 



6-2416 00242 



0-2375 0-0267 



oj;V' 0-0290 



02298 0-0337 



0-2262 0-0380 



o jjjS 00450 



11 ?it|li 0-0485 



n 2166 00544 



The theoretical brightness is greatest on October 12, 

 hut the physical brightness is likely to increase up to 

 the time of perihelion. 



BORRELLY'S ('i)MIU.--The following ephemeris for 

 Greenwich midnight is by 1.. v. Tolhay (Astt. N&ck.; 



wss) ; — 



Date R.A. S. Heel. I.03 r Log 2. 



h. in. -s. . . 



The cornel i I an easj telescopic object al 



tlie end of < ). ;■ November. 



The New Stai i Prelimiriar-} accounts ©f 



photographs ol the i lova \quila- obtained 



at the Lick and Mount ' ilsi n observatories have 



been given In Dr. t, Paddock and by Messrs. 



W. S. Adams and VII | Vst, Soc. I'ac, 



ol w\.. No. 170). Observi i re commenced 



Mount Hamilton on [urn [ouni Wilson 



Inne S, and in each ca nolude the 



as well as the photographii | spectrum. 



riptions of the spectra are in general accord 



2552; VOL. 102 ! 



v iih previous mnts, and show- that the nova fol- 

 lowed thi usual spectral transformation. Among othei 

 details Dr. Paddock refers to thi extraordinar 

 in position and intensity which took place in a pan 

 of absorption lines al wave-lengths 4058 and 4064. 

 I'he green nebulai run was firsi recorded on June 23, 



and the line $.363 on June 22. \ table oi hands 

 measured on a plati taken on June 21 includes lines 

 in the red al 6299, 6367, « >-4» »7, besides Ha, and lines 

 in the yellow al ,v s 7'> <l> ), 5753i mid 5675- ' '"' 

 Mounl Wilson observers classifj the earliesl spectrum 

 of the nova as of type \, with ven broad haz) hands 

 of hydrogen, displaced aboul 20A to the violet. The 

 magnesium line 44s 1 w as also present, and displaced b; 

 the same amount. Of special interest is the observation 

 that a large number of the absorption lines on June 11 

 could I" identified with lines in a Cygni, when allow- 

 ance was made (01 a displacement of the nova spec- 

 trum amounting to 20A al ll-y, and directly propor- 

 tional to the wave-length in the case of other lines. 

 The nebular hands at 4363 and 5007 wen- indicated 

 as e.irh as June 20, ami the latter had Income well 

 marked In June 23. 



Numerous observations of the nova are summarised 

 in Circulai No. 208 of the Harvard College Observa- 

 tory. The firsi record al Harvard was on Maj ^~\ 

 i.sss, when the photographic magnitude of the star 

 was 10-5, and from thai date to June 3, miS, a~ shown 

 on 405 plates, the brightness was subject to small 

 hut undoubted changes. On June 7 the star was of 

 the ''ih magnitude., and on the following night brighter 

 than isi magnitude. Subsequent observations are 

 tabulated to Jul) 22, and show that after the si.u 

 In -an iii fade ih, light fluctuated h\ half a magnitude 

 at intervals of aboul ten days. The oscillations were 



accompanied In marked changes in a line al (nyi ih 

 the spec irum of the nova. 



A large number of estimates of the- brightness of the 

 nova are also included in an interesting article by 

 M. Flammarion which appears in the August issue bf 

 / ' I slronomie. 



Till: METALLOGRAPHY OF TUNGSTEN 

 STEELS. 



MANY investigations of tungsten steels have been 

 made, but there has, as yet, been no sys- 

 tematic stud) of them, and their structural constitu- 

 tion is almost unknown. The steels themselves base- 

 long been important in an industrial sense, in that 

 tungsten is an essential constituent of many magnet 

 and rapid-cutting tool steels. The remarkable 'act 

 that the initial temperature from which they are 

 cooled and the rate of cooling determine the- position 

 of the critical points has long been familiar to metal- 

 lurgists, but hitherto there has been no completeh 

 satisfactory explanation of it. The publication of a 

 systematic study of the magnetic qualities and 

 metallography, not only of the tungsten sic 1 U, but 

 also of carbonless iron-tungsten aliens, by Honda SUjd 

 Vim. il .ami in the recently issued science report (vol. vi.. 

 No. 5) of the Tohoku University is therefore to be 

 welcomed. 



The authors have constructed a pi«liminar\ equili- 

 brium diagram of the iron-tungsten system, from 

 which it appears that only one compound, 1-V.W , as 

 put forward by Arnold and Read, exists. At ordinary 

 temperatures iron dissolves this tungstide up In .1 con 

 centration corresponding with g per cent, of tungsten. 

 In stieU which contain tungsten above this concentra- 

 tion the tungstide appears as small globules scattered 

 through the crystals, which wen- formerly ebnsidered 

 to be a double carbide of iron and tungsten. 



In tungsi.-n steels the tungsten exists eithei as the 



