April 8, 1Q22] 



NATURE 



455 



Messrs. A. Gallenkamp & Co., of Sun Street, 

 E.G., have issued a catalogue of the latest forms of 

 electrical resistance furnaces manufactured bv them 

 for various purposes. The heating element consists 

 of a special alloy in the form of wire or strip, wound 

 over a silica tube or muffle, and the furnaces are so 

 constructed that the element may readily be removed 

 by the user when burnt out, and replaced by a spare 

 part. The maximum working temperature is 1000° C, 

 and special types of furnace are made for the deter- 

 mination of carbon in steel, the estimation of ash in 

 coal, the Lessing coking test for coal, and for organic 

 combustions. The ordinary patterns are suited to 

 such operations as the heat treatment of specimens 

 of metals, the determination of the critical points of 

 steel, and the checking of pyrometers against a 

 standard. The power consumed by the furnaces 

 wlien working at 1000° C. ranges from 400 watts for 

 a tube 12 inches long and i inch diameter to 2300 

 watts for a muffle 14x7x4! inches. Details of 

 accessories such as rheostats for controlling the 

 temperature, ammeters, etc., are given, and the 



prices are also stated — a feature often absent from 

 modem catalogues. 



A NUMBER of reprints of communications made to 

 the Edinburgh meeting of the British Association 

 have been issued from the office of the Association 

 in Burlington House, Piccadilly, W.i. We have 

 received numbers 1-7 as follows : (i) Science and 

 Ethics, by Dr. E. H. Griffiths, ^d. ; (2) The Structure 

 of Molecules, (^. ; (3) The Effects of the War on 

 Credit, Currency, Finance, and Foreign Exchanges, 

 15. 6c?. ; (4) Complex Stress Distributions in Engineer- 

 ing Materials, 35. td. ; (5) Charts and Pictures for 

 Use in Schools, is. ; (6) An International Auxiliary 

 Language, is. ; and (7) Report of the Conference of 

 Delegates of Corresponding Societies, which contains 

 Sir Richard Gregory's presidential address, " The 

 Message of Science." It will be a great convenience 

 to have these discussions and reports in pamphlet 

 form, and it is to be hoped that the demand for these 

 reprints will justify the Association in publishing 

 similar reprints of contributions to future meetings. 



Our Astronomical Column. 



A Study of Obscure Nebula. — There have been 

 many notes in recent years, on regions of the sky 

 where there is a deficit in the star-density as com- 

 pared with neighbouring regions, the explanation 

 generally assigned being an obscuring veil of dark 

 nebulosity. We may refer in particular to one in 

 Mon. Not. R.A.S. for November 1920 dealing with 

 some barren regions in Taurus as shown on the 

 Franklin Adams charts. Rev. J. G. Hagen, S.J., 

 Director of the Vatican Observatory, has been ex- 

 amining these regions for the last ten years with the 

 16-inch refractor at the Observatory. He states that 

 he can see these nebulosities, not as dark objects, 

 but as faintly luminous ones. He discusses their 

 distribution in Scientia for March ; they are seen in 

 all parts of the sky, but are densest towards the 

 galactic poles, and diminish in extent, and density -as 

 the galaxy is approached. He states that they are 

 entirely absent in rich galactic star fields, and sup- 

 poses that the nebulous material has been wholly 

 transformed into stars in these regions. He places 

 the obscure nebulae outside the galaxy and asserts 

 that their greater faintness in low galactic latitude 

 is the result of greater distance ; this does not appear 

 to be sound, as the surface brightness of objects of 

 sensible area is unaffected by distance provided that 

 the intervening space is perfectly transparent. There 

 is the further difficulty that in such barren fields as 

 those in Taurus there is a deficiency not only of 

 distant stars, but apparently also of nearer ones, sug- 

 gesting a much smaller distance for the obscuring cloud. 

 Thus while the visual study of these interesting 

 regions is thoroughly useful work, there seems to be 

 need of further examination of the significance of 

 the results obtained. 



Spectroscopic Study of Procyon's Orbit. — 

 Dr. Lunt directs attention in Astrophys. Journ. for 

 January to the aid that the spectroscope may render 

 in the study of this system. The companion, dis- 

 covered by Schaeberle in 1896, is a very difficult 

 object and observations have been scarce of late. 

 Dr. Lunt quotes the figures that he deduced from 

 his measures on plates taken between 1909 and 1912. 

 These appear to indicate a diminution in the approach 

 of the principal star to the sun, which was 3-74 



NO. 2736, VOL. 109] 



km./sec. in 1909 and 3-56 km./sec. in 1912 ; he points 

 out that observations made now will be fairly de- 

 cisive as to the pose of the orbit-plane, as there 

 would be a difference of i-^- km./sec. on the two 

 assumptions. As one of the nodal passages is now 

 at hand, the conditions are more favourable than 

 they will be till 1938, when the other node is passed. 

 He is himself arranging for a series of plates and 

 asks for co-operation elsewhere. The approach of 

 the centre of gravity towards the sun is given as 

 3-52 km./sec. ; corrected for the sun's motion, the 

 system is approaching with a speed of 19 km./sec. 

 in a line inclined 14° to the line joining sun and star. 



Recent Magnitudes of Nov^. — The appearance 

 of a new star in the heavens at once attracts the 

 attention of a large number of observers who follow- 

 very carefully the changes of magnitude and the 

 variations in its spectrum. When, however, the 

 magnitude has dwindled down to about 8 or 9, interest 

 greatly diminishes ; the star becomes too faint for 

 spectroscopic analysis except with large .telescopes, 

 and the small and slow changes of magnitude are not 

 watched by many observers. It is, however, very 

 important to follow novaj so long as possible in order 

 to keep in touch with the later variations. Great 

 interest is, therefore, attached to the series of observa- 

 tions made by Dr. W. H. Steavenson of six novx 

 during the summer and autumn of 192 1 {Monthly 

 Notices. R.A.S., vol. 82, November 192 1). Nova 

 Ophiuchi (1848) gave evidence of variability in a 

 period of about fifty days, the magnitudes varying 

 from about 12 to 13. Nova Aquila; (191 8) is still 

 slowly waning, the mean magnitude falling from 9-4 

 to 9-9, with a possible long-period variation. Nova 

 Cygni (1920) is also still fading slowly, the mean 

 magnitude during the period of observation falling 

 from 9-4 to lo-o. Nova Cygni (1876), a star now very- 

 near the limit of visibility, exhibited practically a 

 constant magnitude, namely, 14-81. The same is the 

 case with Nova Lacertae (1910), which has varied only 

 01 mag. from 14-1. On the other hand. Nova Persei 

 (1901) has shown a marked variability of an irregular 

 type, the two extremes of brightness being 12-27 and 

 13-36. The star was accompanied by a small patch 

 of nebulosity about 5" in diameter. 



