124 



NATURE 



[September 23, 1920 



breaking down the more complex molecules into 

 simpler ones by means of heat. This operation, which 

 in its modern forms the lecturer dates bacli to a patent 

 issued in 1890 to the late Sir Boverton Redwood and 

 Sir James Dewar, is considered to be the most 

 promising way of increasing supplies of petrol from 

 petroleum sources. 



Among points of interest in the report (Cmd. 881) 

 of the Government Chemist on the work of his 

 department during the past financial year we note 

 that radium was extracted from many thousands of 

 luminous dials, compass-cards, gun-sights, and similar 

 materials made for use during the war. The extrac- 

 tion was complicated by the overwhelming proportion 

 of paint with which the radium was mixed, but prac- 

 tically all was recovered and converted into a form 

 suitable for further use at a comparatively small cost. 

 For the Board of Trade 532 samples of the potash 

 material supplied by Germany to this country were 

 analysed. The samples taken were divided into three 

 portions ; one was analysed in Germany, another here, 

 and the third retained in a neutral country for refer- 

 ence in case of dispute. The report, however, does 

 not indicate whether any dispute actually arose. 

 Incidentally, in connection with other samples, a 

 method was worked out for differentiating between 

 sodium chloride and potassium chloride in solid caustic 

 potash. A good deal of work was done on the deter- 

 mination of the nature and proportion of the possible 

 toxic constituents which might be present in water 

 receiving drainage from tarred roads. In the course 

 of this work new and delicate methods for detecting 

 some of the substances were devised. Carbolic acid, 

 for instance, can now be detected and estimated when 

 present in even smaller proportion than one part in a 

 million parts of water. The total number of samples, 

 368,898, dealt with during the year showed an increase 

 of nearly 80,000 compared with the previous year. The 

 principal increases were due to imported goods, such 

 as wine, sugar, tea, and cocoa ; they are indicative of 

 the revival of trade after the return to peace conditions. 



We have just received the Lincolnshire Naturalists' 

 Union Transactions for 1919. The first portion of 

 the volume is devoted to the annual reports of the 

 sectional officers, recording, in most cases, the work 

 which has been done during the past year in their 

 own departments. The report from the botany section 

 is somewhat different; it consists of notes selected 

 from observations on seed-dispersal which have been 

 made during the past fifty years by the sectional presi- 

 dent and his colleagues. The methods adopted by birds 

 for the transportation of seeds over long distances are 

 mentioned, and the remainder of the report is given 

 over to a list of the agents and ■methods bv which the 

 seeds of the commoner trees are dispersed. A complete 

 list of the author's observations, which he promises 

 to publish in a future volume, "The Flora of Lincoln- 

 shire," will be welcomed by ecologists. The volume 

 also includes lists of marine shells of the Lincoln- 

 shire coast by Mr. A. Smith, and of non-marine 

 mollusca of the county, contributed bv Mr. J. W. 

 Musham from data obtained from the manuscripts of 

 the late Mr. W. J. Roebuck. 



NO. 2656, VOL. 106] 



Our Astronomical Column. 



Another Quickly Movi.sg Dwarf Star. — Mr. 

 Innes's zeal in examining pairs of plates with the 

 blink micrometer has been rewarded by the discovery 

 of another very interesting dwarf star with a large 

 proper motion and parallax. The former was detected 

 from plates taken at Sydney, the latter from a series 

 of fourteen plates taken at Johannesburg with the 

 Franklin-Adams lens. The star is of the 12th magni- 

 tude; its position for 1920 is R..^. iih. 12m. 52-393., 

 S. decl. 57° 8' 13-1''; the proper motion in R.A. is 

 -2-506", in decl. +0-973', total 2-688' in P. A. 291-2°. 

 The parallax from R.A. measures was found to be 

 0350", that from declination measures 0-324". 



The proper motion of aCentauri is 3-68" in P..\. 

 281-4°. That of the present star is sufficiently near 

 this to suggest that it may belong to the same system. 

 Mr. Innes notes that if this were the case its parallax 

 would be about 0-5''. It is not stated whether he 

 took the radial velocity of aCentauri into account; 

 in any case, the observed parallax is sufficiently near 

 to render the assumption of connection tenable. 



Prof. Barnard's Observations of Nova Persei. — 

 Prof. Barnard puts the Yerkes refractor to good use 

 in continuing to observe novae long after thev have 

 become too faint for ordinary observers. The Monthly 

 Notices, R.A.S., for June contains his observations 

 of Nova Persei, 1901. Its light is still subject to 

 fluctuations ; thus it rose from 13-7 to 12-6 between 

 1919 November 15 and 18, declining again to 13-7 in 

 the three following days. The mean value in 1920 

 is 13-48, and the progressive decline appears to have 

 ceased. L'nlike some other novse, its aspect does 

 not now differ from that of an ordinary star, and 

 Prof. Barnard considers that it has returned very 

 closely to its condition before the outburst. Micro- 

 meter measures of position appear to show a slight 

 proper motion of the nova relativelv to faint adjacent 

 stars, the centennial displacement being i-o8' in the 

 direction of diminishing R..\. and 2-20' S. 



It is noted that the period required to decline to 

 the pre-nova condition varies in different stars between 

 eight and fifteen years, which is surprisingly short, 

 considering the tremendous character of the outburst. 



The Bergedorf Observatory, Hamburg. — Vol. ii , 

 Nos. 3-5, of the Abhandlungen of this observatory, 

 which has just been issued, contains a useful cata- 

 logue of the positions, magnitudes, and colour-indices 

 of the stars in the Pleiades (584 in number) down to 

 mag. 14. The magnitudes were determined by 

 observations with two wedge-photometers. Com- 

 parison with Hertzsprung's photographic catalogue 

 shows that the visual magnitudes of the fainter stars 

 are brighter in the mean by 07. The colour-indices 

 increase rapidly from mags. 3 to 10, remaining 

 fairly constant after this. Comparison is also made 

 between the number of stars in each half-magnitude 

 interval and the number to be expected in an average 

 region of the same area in galactic latitude 237°, 

 using the table of Van Rhijn. For stars brighter 

 than mag. 11 the excess is more than threefold; it 

 then pradually declines, reaching zero at mag. 13^. 

 .\nother essay discusses the planetary obser\'ations 

 made from 1909 to 1920. An interesting round dark 

 spot on Juoiter had the abnormally large rotation 

 period of gh. 5813m. from 1Q20, February 17 to 

 March 18 ; it then split into two portions, one retain- 

 ing the same rotation period, while the other had the 

 value gh. 53-5m., from observations between March 27 

 and .'\pril i. There is also a study of the contour 

 lines of equal luminosity in the Milky Way (north of 

 decl. —25°). The brightest regions are between 7 and 

 (S Cvgni and in Sagittarius. 



