886 



NA TURE 



[December 30, 1922 



dilute sulphuric acid two lead plates pasted with 

 an oxide of lead — that is to say, using plates of the 

 same nature as are used in secondary cells. The 

 aluminium electrolytic condenser is an electrostatic 

 type of condenser, whereas in the arrangement of 

 pasted lead plates in dilute sulphuric acid the energy 

 is stored in the form of chemical energy, and it is 

 in this respect that the novelty of the new type of 

 condenser appears. " For this reason," Dr. Wall 

 adds, " the term ' electro-chemical condenser ' more 

 correctly describes the action of the pasted lead plate 

 arrangement than the term ' electrolytic condenser.' " 



The third edition, recently issued, of the General 

 Catalogue of the Oxford University Press is a volume 

 of 480 pages. Supplementary to the catalogue itself 

 is an alphabetical list of authors and editors extending 

 to no less than 128 pages. A preface gives some 



interesting statistics, and the activity of the press is 

 illustrated by the fact there stated, that it publishes, 

 in one way and another, more than two books every 

 day. The fifth section of the catalogue deals with 

 books on natural science, including mathematics, 

 physics and chemistry, astronomy, geology, biology, 

 and the history and methods of the sciences. The 

 present volume is more than a mere catalogue ; 

 besides giving many bibliographical details — including 

 size in inches, number of pages, and date of publica- 

 tion — it sets out the full contents of books in several 

 volumes and of joint works by several authors. It 

 describes not only all Clarendon Press books, but also 

 all books published by the press for learned societies 

 other than the University of Oxford. The fact that 

 many of these books are in their nature unremunera- 

 tive affords good evidence of the service rendered by 

 the press to the cause of education and learning. 



Our Astronomical Column. 



Great Meteor of December 6. — This brilliant 

 object passed over Lincolnshire at n h 40"' and 

 illuminated the north-east part of England with 

 remarkable intensity. It was seen so far away as 

 Armagh in Ireland, where the observer considered 

 that its refulgence overpowered the light of the moon. 

 A number of observations have been received, and 

 they indicate that the radiant point was in Taurus 

 at about 56 +8°, and that the luminous flight of 

 the object commenced in the neighbourhood of 

 Grantham ; its direction was north-north-west. It 

 passed nearly over Lincoln and Grimsby, and at the 

 latter place its height appears to have been 24 miles. 

 Continuing its course, it fell to about 2 miles in height 

 when a short distance south-east of Hedon, near Hull, 

 and about 2 miles further on probably fell to the 

 ground. No meteorite has, however, been reported 

 as having been discovered up to the time of writing, 

 but such an object might very easily escape detection. 



The meteor appeared so late at night that, in spite 

 of its great lustre, it was noticed by comparatively 

 few observers. 



Stellar Temperatures and Planetary Radia- 

 tion. — In an earlier communication, Dr. W. W. 

 Coblentz gave estimates of the temperatures of sixteen 

 stars as determined from their spectral energy 

 distribution, which was obtained by means of a new 

 spectral radiometer, consisting of a series of trans- 

 mission screens and a vacuum couple. By means of 

 these screens, which, either singly or in combination, 

 had a uniformly high transmission over a fairly narrow 

 region of the spectrum and terminated abruptly to 

 complete opacity in the rest of the spectrum, it was 

 possible to obtain the radiation intensity in the 

 complete stellar spectrum as transmitted by our 

 atmosphere. The standard used for comparison was 

 a solar type star a Auriga;, type Go. Being now 

 equipped for making radiometric measurements of 

 the sun, the effective temperature of which is known 

 with a considerable degree of accuracy, Dr. Coblentz 

 communicates the results of this comparison in the 

 Proc. of the U.S. National Academy of Sciences, 

 Vol. 8, No. 11, Nov. 1922. In this he describes the 

 apparatus and method of procedure. He finds the 

 agreement between the observed temperatures of a 

 Auriga; and the sun satisfactory, and thus verifies the 

 previous measures of stellar temperatures, which 



NO. 2774, VOL. I io] 



range from 3000 K for red, class M stars, to 12000 K 

 for blue, class B stars. In the case of the planets, 

 Dr. Coblentz differentiates between the thermal 

 radiation as a result of warming by exposure to solar 

 radiation and the heat radiated by virtue of a possible 

 high internal temperature of the planet itself. The 

 planetary radiation he finds increases with decrease 

 in the density of the surrounding atmosphere, and as 

 a percentage of the total radiation emitted he gives the 

 following values : Jupiter o, Venus 5, Saturn 15, 

 Mars 30, and the Moon 80. 



Spectroscopic Parallaxes of B Stars. — Mr. 

 D. L. Edwards read a paper at the meeting of the 

 Royal Astronomical Society in November on the 

 pioneer work on these stars that has been carried 

 out at the Norman Lockyer Observatory, Sidmouth, 

 where 200 negatives have been studied and the 

 intensities of various lines correlated with respect 

 to type and absolute magnitude. 



The helium lines at 4472 and 4026 were found to 

 be good indexes of spectral type, and by their aid 

 some gaps in the Harvard series were filled. Line 

 4472 was found to vary also with absolute magnitude. 

 The measures of the intensities of lines could be 

 made very accurately by noting the point of dis- 

 appearance in a darkened wedge. 



The difficulty in getting absolute magnitudes was 

 that very few trigonometrical parallaxes of B stars 

 had been obtained. It was necessary to use also 

 parallaxes derived from proper motions, and the 

 hypothetical parallaxes already published for many 

 binary stars. In the discussion it was noted that 

 the assumed mass iised in getting the latter was 

 twice that of the sun, but that this is probably too 

 small for B stars. The use of a larger mass would 

 reduce the hypothetical parallax. For this and other 

 reasons it was felt that, while there was every reason 

 to believe the method would prove a very useful 

 one, it was advisable to look on the calibration 

 of the curves as provisional. Mr. Edwards used 

 Kapteyn's value, o"-04, for the parallax of -n Tauri {in 

 the Pleiades), but some recent determinations give 

 o"-oi. 



It is of particular importance to extend our know- 

 ledge of the limits of absolute magnitude of the 

 B stars, since the results will have important bearing 

 on the distances of the globular clusters. 



