292 



NATURE 



[August 25, 1923 



The Board of Trade accordingly desires it to be known 

 that an order will be made in due course, removing 

 the names of the copper and green pheasants from the 

 Schedule, with effect from January i, 1924. 



Science announces that the committee of the Daniel 

 Giraud Elliot Medal desires to receive nominations 

 for the awards of the years 1921 and 1922, which are 

 still open, because the committee has not been able 

 to reach unanimous conclusion on any work thus far 

 brought to its attention. The Elliot Medal is awarded 

 for some especially great contribution, not for general 

 accomplishment, in the field of either zoology or 

 palaeontology. It is not restricted in either branch to 

 the vertebrates, but may be made in either the 

 vertebrate or invertebrate field and is open to scientific 

 workers of the world. The award of the gold medal is 

 accompanied by a generous honorarium. Nominations 

 for the two years mentioned, namely, 192 1 and 1922, 

 and also for 1923, can now be received. Communi- 

 cations should be addressed to the Secretary of the 

 National Academy of Sncciees, Washington, D.C. 



The eleventh meeting of the Indian Science Con- 

 gress will be held at Bangalore on January 14-19, 1924. 

 H.H. the Maharajah of Mysore will be patron of the 

 meeting, and Sir Asutosh Mookerjee will be president. 

 The following sectional presidents have been ap- 

 pointed : — Mr. B. C. Burt (agriculture) ; Prof. C. V. 

 Raman (physics and mathematics) ; Dr. E. R. Watson 

 (chemistry) ; Prof. K. N. Bahl (zoology) ; Prof. 

 Agharkar (botany) ; Mr. H. Bosworth Smith (geology) ; 

 Lieut. -Col. Christophers (medical research) ; Mr. J. 

 Hornell (anthropology). The honorary local secre- 



taries will be Prof. F. L. Usher, Central College. 

 Bangalore, and Mr. S. G. Sastry, Secretary, Board of 

 Scientific Advice, Bangalore. Further information 

 can be obtained on application to the hon. general 

 secretary, Dr. J. L. Simonsen, Forest Research 

 Institute and College, Dehra Dun, U.P. India. 



The Journal of the Rdntgen Society (the oldest 

 radiological society in the world) for July (vol. xix. 

 No. 76) contains an account of the twenty-fifth 

 anniversary dinner of the Society held in March last, 

 and a translation of Rontgen's first and second 

 memoirs on X-rays, entitled " Concerning a New 

 Kind of Ray," which are interesting reading. 



The latest catalogue (No. 378) of Messrs. Bernard 

 Quaritch, Ltd., 11 Grafton Street, W.i, is of a mis- 

 cellaneous character, but of the 1399 second-hand 

 works offered for sale many deal with science, and, 

 as is usual with the lists issued by this firm, 

 some are very scarce and choice. The catalogue 

 also comprises a list of selected new and recent 

 publications. 



The McGraw-Hill Publishing Co., Ltd., announces 

 an interesting new series of books under the title of 

 " Concise Studies in Economic Problems," which will 

 embody the results of research studies made by the 

 Institute of Economics of Washington, D.C, U.S.A. 

 The first volume will be " Germany's Capacity to Pay." 

 Succeeding works will deal with International 

 Economic Reconstruction, International Commercial 

 Policies, Industry and Labour, and Agricultural 

 Economics. 



Our Astronomical Column. 



The Density of the Corona. — The question of 

 the density of the corona is of interest both with 

 regard to possible refraction of starlight in the in- 

 vestigation of the Einstein light-deviation, and with 

 regard to the amount of resistance met with by 

 comets of small perihelion distance. Astr. Nach., 

 5238, contains a discussion of the subject by B. 

 Fessenkoff, of Moscow. 



The author assumes that the total light of the 

 corona is equal to that of the full moon, and that the 

 light intensity varies (i) as the inverse square, (2) as 

 the inverse fourth power, of the distance from the 

 sun's surface. He utilises some studies of his own on 

 the light-reflecting powers of the terrestrial atmo- 

 sphere at various heights, obtained from measures of 

 the brightness of twilight for different angles of de- 

 pression of the sun. He calculates that the light 

 given by a small volume of the corona, 5' from the 

 sun's limb, in terms of the light given by an equal 

 volume of terrestrial atmosphere, of the density and 

 composition that exist at a height of 100 km., placed 

 in the same situation as the coronal volume, is : — 

 on supposition (i) 0'52 x 10"' ; on supposition (2) 

 0-27 X 10"*. The density of the corona at 5' from the 

 limb is that of hydrogen at pressures 0-43 x lo"* mm. 

 and 0'22 X 10-* mm. (temperature 0° C.) on the two sup- 

 positions. It will be remembered that the nearest 

 stars that have been observed in the Einstein in- 

 vestigation were considerably further from the limb. 



Report on the Kapteyn Selected Areas. — 

 Prof. Van Rhijn, of Groningen, has issued a useful 



NO. 2808, VOL. 112] 



report on the progress of researches on these areas. 

 They are distributed on a uniform plan over the 

 celestial sphere, and are to be studied in an exhaustive 

 manner by a number of co-operating observatories. 

 The first step is the formation of a photographic 

 Durchmusterung of the stars in the areas ; this is 

 being done at Harvard and Arequipa, with apertures 

 of 16 and 24 inches, and limiting magnitudes 15-9 and 

 16-3 respectively ; these plates are being measured at 

 Groningen. It is estimated that the number of stars 

 is about a quarter of a million, the total area being 

 225 square degrees, or 1/183 of the sphere. The 

 positions are determined to an accuracy of half a 

 second, the magnitudes to o-i mag. The centennial 

 proper motions of the stars of mag. 12 and brighter 

 are determinable to a third of a second with the aid 

 of the Carte de del plates ; those of the fainter stars 

 will not be obtainable for some years with the neces- 

 sary accuracy. 



The best methods of determining absolute motions 

 and eliminating magnitude error are discussed ; the 

 author hopes that Kapteyn 's plan for a photographic 

 parallax Durchmusterung will not be abandoned. He 

 admits that the results are illusor}' for particular 

 stars, but he thinks that they will serve to compare 

 the parallaxes of stars of the same magnitude with 

 large and small proper motions. The colour-indices 

 are being determined by Seares by comparison of 

 photographs on ordinary and orthochromatic plates. 

 Altogether the report gives a hopeful summary' of the 

 results already attained and those to be looked for in 

 the near future. 



