June 9, 1921] 



NATURE 



471 



by the bleaching agent or by the attempt to replace 

 it, by the spreading of the ink caused by the removal 

 of the size, by the restoration to visibility by chemical 

 means of the bleached-out writings, by the finding of 

 the bleached inscriptions by photography under suit- 

 ably coloured lights, and so on. The article is illus- 

 trated with excellent photographs and reproductions 

 of photographs. 



On May lo, at the Institute of Petroleum Tech- 

 nologists, Prof. P. Carmody (late Government analyst, 

 Trinidad) read a paper on "Trinidad as a Key to the 

 Origin of Petroleum." Prior to the meeting the title 

 of the pa|>er had created much interest and curiosity, 

 •especially among- those members who have had pro- 

 fessional experience in the island, but unfortunately 

 both the paper and subsequent discussion were 

 scientifically somewhat disappointing. The author's 

 main contention was that in a comparatively small 

 area, within reasonable access of Europe, and under 

 conditions of life peculiarly satisfactory for a tropical 

 island, there exist all the requisite natural factors 

 for an exhaustive research into the origin of petro- 

 leum, as yet a little understood problem the solution 

 of which must perforce have far-reaching scientihc 

 and economic results. The natural factors referred 

 to include the occurrence of varied forms of solid, 

 liquid, and gaseous hydrocarbon compounds within 

 the rocks of the island, and in illustration of his idea 

 the author gave a brief description of these, supple- 

 mented with a large number of chemical and physical 



data obtained during the course of some thirty years' 

 work in the Government laboratory. There is obvious 

 value in the publication of such data bv one whose 

 long experience entitles him to speak with authority, 

 but the raison d'etre of the paper suffered much from 

 the somewhat narrow view taken as to the origin 

 of oil, viz. its derivation entirely from vegetable 

 matter, i.e. cellulose. On this assumption, and in 

 view of the many known oil occurrences wherein 

 marine organisms have unquestionably been involved, 

 it is doubtful whether Trinidad does indeed constitute 

 the desired "key," and whether, as the president 

 remarked later, the existence of all these forms of 

 petroleum is not a disadvantage rather than an aid 

 to the solution of the problem. 



Prof. R. S. Trolp, of the forestry department of 

 the University of Oxford, has written for publication 

 by the Oxford University Press a work in three 

 volumes on "The Silviculture of Indian Trees." The 

 first volume, dealing with Dilleniaceae to Leguminosae — 

 Papilionaceae, is promised for appearance by an early 

 date. 



A FULL report of the meeting held on May 30 by 

 the National Union of Scientific Workers on "The 

 Administration of Scientific Work," of which a short 

 account was given in last week's Nature, p. 439, 

 will appear in the next issue of the union's Journal. 

 Copies may be obtained from the Secretary, 

 N.U.S.W., 25 Victoria Street, S.W.i, at the end of 

 this month (post free 6d.). 



Our Astronomical Column. 



Comets.— Reid's comet is rapidly fading, but should 

 be within reach of moderate instruments for another 

 nionth. An extension of the ephemeris from Ebell's 

 elements for Greenwich midnight is therefore given : 



R.A. N. Decl. 



R.A. N. Decl. 



June 



9 



17 

 21 

 2? 



8 833 

 8 10 41 

 8 1237 

 8 14 24 

 816 3 



Values of log r, 



5138 



49 35 



4748 



46 13 

 4448 

 log A 



June 

 July 



June 13 



8 17 41 

 8 19 16 

 8 20 49 

 8 22 19 

 823 46 



00665, 



43 31 

 42 21 

 41 18 

 40 19 

 3924 

 0-2311; 



June 25, 01054, 03035; July 7, 01459, 03543 



The following observation of Pons-Winnecke's 

 comet was obtained at Greenwich : G.M.T. June 2d. 

 loh. 57m, 38s. ; apparent right ascension, 

 2oh. 37m. 15-858. ; apparent north declination, 

 37° 12' 45-8". The position deduced from Crawford 

 and Levy's second elements is right ascension 

 2oh. 38m. 5s., north declination 37° 3'. The elements 

 are therefore fairly near the truth. 



The comet now appears large and diffused owing 

 to its small distance from the earth. It will be nearest 

 to both earth and sun on June 12. 



Mr. G. Merton obtained an observation of Dubiago's 

 comet on June r. He states that its position agreed 

 closely with the ephemeris given in Nature of May 26. 



Nova Cygni III. (1920).— Mr. Denning writes that 

 he observed this object on June 5 at loh. 40m. G.M.T. 

 with a 6i-in. refractor; He estimated the magnitude 

 to be 9-6, so that the star's light would appear to have 

 declined very slightly during the last ri months. It 

 will be remembered that the magnitude of the star 

 decreased from i-8 to 85 during the -t days from 

 NO. 2693, VOL. 107] 



j August 24 to October 6, 1920, so that the average 

 decline of light was o-i6 per day. Since about the 

 middle of October, however, the nova appears to 

 have maintained its brightness in a rather unex- 

 pected way. 



Collision of Star and Nebula. — Prof. Ernest W. 

 Brown contributes a paper on this subject to the April 

 issue of the Astrophysical Journal. Taking the star 

 as origin and the line of relative motion as the Z-axis, 

 particles of the nebula equidistant from this axis 

 would all be deflected into similar hyperbolic orbits 

 meeting in a point on the axis. There would thus 

 be numerous collisions of particles along the axis 

 which would generate a fan-shaped nebula with its 

 apex towards the star. Another nebulous envelope 

 surrounding the star would be formed by collisions of 

 particles with the star or its appendages". The nebula 

 is supposed to be non-gaseous at the start, being com- 

 posed of widely scattered particles. 



Hubble 's variable nebula round the star R Mono- 

 cerotis is discussed in detail, and it is shown that its 

 form agrees closely with that indicated by the theory. 

 It is suggested that the variations in the' light of the 

 fan-shaped appendage may arise from irregularities in 

 the density of the nebula that the star is supposed 

 to be traversing. It is shown that Prof. Slipher's 

 observation that the stellar envelope and the fan- 

 shaped appendage have identical spectra is in accord 

 with the hypothesis, for both would arise from the 

 gas resulting from collisions of the nebular particles. 

 Slipher and Lampland's further statement that the 

 spectra resemble those of novae in their early stages 

 suggests to Prof. Brown that a similar explanation 

 may be available for the phenomena of novae. 



