July 3, 1919] 



NATURE 



353 



The governing body of the College of Science, 

 University of Calcutta, has expressed a desire that 

 the researches undertaken in the various departments 

 of the college should be published from time to time 

 in the form of memoirs or bulletins. Through the 

 courtesy of Sir Prafulla Chandra Ray, we have re- 

 'oived a copy of the first of these memoirs issued by 

 ;io department of chemistry; it is a volume devoted 

 10 the organic thio-comf>ounds. Some of the paf>ers 

 have already appeared in a condensed form in the 

 Journal of the Chemical Society ; these have been in- 

 corporated with additional matter so as to present a 

 connected account of the thio-compounds which jrive 



I rise to tautomeric changes and to the formation of 

 polysulohonium derivatives. The author remarks that 

 time alone can show whether there will be a con- 

 tinuity in the regular issue of such memoirs, and 

 warns those who intend to pursue chemistrv in India 

 that they must not expect to reap a rich harvest in 

 the near future. For a thousand years or more India 

 J has been a tdhu\a rasa so far as the cultivation of 

 the physical sciences is concerned. " We in the East 

 have been living in silent and ecstatic meditation." 

 Pioneers in the introduction of Western science have 

 no native tradition to follow up : they must formulate 

 their own schemes and carry them out as best they 

 mav. .At the same time, the work already turned 

 I out bv some of the pupils is full of hopeful aueurv for 

 r the future. 



Messrs. Dulau and Co., Ltd. (34 Margaret Street, 

 W.i), are offering for sale (in Catalogue No. 76) 



(some nine hundred works in geologv and palseonto- 

 logy, entomology, botany and agriculture, geography 

 and travel. The list contains several scarce items, 

 and long runs of scientific serials, but for the most 

 part it deals with volumes of current interest and 

 value, and the prices asked are most moderate. The 

 catalogue should be seen by anyone wishing to form 

 or add to a science librarv. 



-\ NOTEWORTHY feature of the latest catalogue 

 (No. 180) of Messrs. W. Heffer and Sons, Ltd., Cam- 

 bridge, is the Oriental library of the late Dr. A. F. R. 

 Hoernle, of Oxford, comprising more than four 

 hundred items (the Sanskrit portion of the library is 

 not included, being promised for a later catalogue). 

 Other works offered for sale by Messrs. Heffer deal 

 with folk-lore, mythology, and allied subjects; there 

 is also a list of recent purchases in science books, 

 manv of which are publications issued abroad. The 

 catalogue is sent free by the publishers upon 

 applicaticn. 



Mr. J. Y. Buchanan, F.R.S., is publishing through 

 the Cambridge University Press a volume entitled 

 '■ Accounts Rendered of Work Done and Things 

 Seen." It will comprise some thirty-three papers, 

 mostly dealing with scientific subjects. .Among them 

 are several from our columns. Others are " Geo- 

 graphv, in its Physical and Economical Relations " ; 

 "A Retrospect of Oceanography in the Twenty 

 "Wars before 1805 " ; " On a Method of Determining 

 the Specific Gravity of Soluble Salts by Displacement { 

 in their own Mother-liquor, and its Application in the | 

 Case of Alkaline Halides " ; "On the Oxidation of 1 

 Ferrous Salts"; "Lakes," and "On the Com- i 

 pressibility of Solids." The essays will be printed in j 

 their original form. Messrs. H. K. Lewis and Co., 

 J Ad., will shortly issue to subscribers "Sir William 

 Osier's Anniversarv Book." which is now in course 

 of preparation by Sir W. Osier's pupils and colleagues 

 numbering about a hundred. 



NO. 2592, VOL. 103] 



OUR ASTRONOMICAL COLUMN. 

 Nova Aquil^.— This temporary star, which ap- 

 peared last year, is slowly pursuing its course of 

 decreasmg brightness, and is now about magnitude 6^ 

 or famter. Observations by Mr. Harold Thomson in 

 the Journal of the British Astronomical Association 

 for May, give 6-14 as the magnitude on March 28, 

 6- 14 on April 26, 637 (the mean of observations with 

 two instruments) on May 22, and 664 on May 26. 

 These magnitudes are determined by comparison' with 

 the neighbouring star B.D.+o°4027, the magnitude of 

 which is taken as 604. Mr. Thomson adds that the 

 visual spectrum strongly resembles that of Nova 

 Gerninorum II. at a similar stage of its career. The 

 continuous spectrum is still visible from about the 

 position of the D line to near H7. The brilliance of 

 the nebula line at 5007 is intense. There is at least 

 j one bright line remaining of the group near D, 

 j which was so conspicuous in the early stages, and 

 I bright lines or bands are still visible near 464 and 

 H7. 



j The Parallax of the Orion Nebula.— The dis- 

 I tance of this well-known nebula, or rather of the stars 

 associated with it, has been determined both bv Prof. 

 Kapteyn and Prof. W. H. Pickering with consider- 

 able divergence in its amount. In both cases the 

 results were deduced by a method which is practicallv 

 comparing the brightness of the stars in question 

 vvith the brightness of stars of the same types the 

 distances of which are assumed to be known. Prof. 

 Pickering obtained the value 00005", whilst Prof. 

 Kapteyn found 00054". I" the April issue of Pub- 

 lications Ast. Soc. Pac. Prof. Pickering attempts to 

 explain this wide discordance by ' the fact that the 

 same stars of the nebula formation were not used in 

 the two investigations, and that the type of spectrum 

 assigned, and therefore luminosity, were different. He 

 now accepts 00020" as the value of the parallax, and 

 considers this to be a maximum value. 



Planetary Nebula. — The 60-in. reflector of the 

 Mount Wilson Observatory is being used by Mr. van 

 Maanen for the determination of stellar parallaxes photo- 

 graphically by the usual method relative to comparison 

 stars. Mr. van Maanen is specially finding the parallaxes 

 of nebulae, and the distances of six of the planetary 

 class have lately been published (communication to 

 the National .Academy of Science, No. 56, reprint). 

 The absolute parallaxes of the central stars range from 

 o-oo8" to 0023", and, the photographic magnitudes 

 having been derived, it is possible to determine the 

 absolute magnitudes, the mean of which for the six 

 nebulae is -I- 9-1. This faint absolute magnitude is 

 noteworthy because the spectra of these objects con- 

 sist in many cases of bright lines, whereas with the 

 stars in general bright-line spectra are usually asso- 

 ciated with high luminosities, some Wolf-Rayet stars, 

 for instance, the spectra of which resemble those of 

 planetary nebulae in some respects, having been found 

 to have a mean absolute magnitude not far from o. 

 The linear dimensions of these objects can obviously 

 be found from their measured angular diameters, and 

 the major axis of the largest of the six, N.G.C. 6720, 

 is given by Mr. van Maanen as 10,000 astronomical 

 units, and the smallest. N.G.C. 7662, as 1350 units,, 

 which may be compared with the orbit of Neptane, 

 the diameter of which is 60 astronomical units. It is 

 to be noted that in the new General Catalogue these 

 six objects are not described as planetary- in every 

 case, the two above-mentioned being in the annular 

 class. 



