November 3. 192 1] 



NATURE 



3>9 



Automobile Engineers deals with the subject of indus- 

 trial standardisation. A little standardisation had 

 been accomplished subsequent to 1910, but the year 

 1914 found us in a condition of partial impotence, 



and gave the 'component assemblers " in America j issue^a'Tist'of additTJns'to their Medical' a^^^ 

 their opportunity for reaping a rich harvest, Co- ■ 



man Industry was formed three years ago, and in 

 two years had issued 160 standard sheets and had 

 more than 400 in progress. 



Messrs. H. K. Lewis and Co., Ltd., have just 



oi>eration in this and other matters with a view to the 

 re-establishment of trade is urgent at the present 

 time. Hitherto British industry has been more or 

 less indifferent to the question of standardisation ; many 

 directors have been, and still are, apathetic in the 

 matter, and vote money for standardisation more in 

 the spirit of charity donations than as matters of 

 important business. Mr. Watson considers it would 

 be best for British makers to concentrate on the 

 standardisation of commonly applicable details rather 

 than to attempt to produce vehicles alike in all par- 

 ticulars. Abroad there will always be found an ap- 

 preciable percentage of distinctive British-built cars 

 owned by discriminating users. Standardisation in 

 foreign countries is irraking great strides ; indeed, 

 there are now ' standards committees in thirteen 

 different countries. A Standards Committee of Ger- 



Circulating Library for the months July-September. 

 The catalogue should be of service to all students of 

 science, whether subscribers to the library or not. 



Messrs. Gurney and Jackson will shortly publish 

 "The Natural History and Physical Features of the 

 Canary Islands : Their Fauna, Flora, and Geological 

 Formation." The work, which will be illustrated by 

 reproductions of photographs and maps, will deal 

 especially with the ornithology of the islands. 



We have received a copy of a short paper ■ On 

 Correlation," by Alf Guldberg, from the Norsk 

 Matematisk Forenings Skrifter. The paper (written 

 in English) criticises the divergent definitions of cor- 

 relation that have been given, and suggests cautions 

 as to interpretation, but there does not appear to be 

 much noveltv in the views of which an exposition is 

 jliven. 



Our Astronomical Column. 



\ 



The November ?.1eteors. — Mr. W. F. Denning 

 writes : — The shower of Leonids is due at the middle 

 of November, and though the parent comet of the 

 stream is now at a great distance from the earth 

 (approaching us from near the orbit of Uranus) there 

 will probably be a tolerably active exhibition of 

 meteors. 



Observations in past years have proved that cer- 

 tain sections of the ellipse are more rich in meteors 

 than others, so that if we assume a period of about 

 thirty-three years for all portions of the stream, the 

 display of November 14, 1888, ought now to be re- 

 peated. The shower of that vear was not of verv 

 special character, but it was fairly conspicuous, and 

 furnished some large fireballs. It was, in fact, con- 

 siderably more striking than an ordinary return of 

 Leonids when Tempel's comet is far removed from 

 perihelion. 



The best time for observation this year will be the 

 morning of the 15th, but unfortunately there will be a 

 full moon in the sky, so that onlv the brighter meteors 

 will be visible. However, the members of the Leonid 

 stream usually supply a number of splendid objects, 

 and tolerably bright meteors are quite a common 

 feature. Though the conditions affecting this year's 

 return are not therefore favourable, the event should 

 be carefully watched, for it is important to accumu- 

 late evidence as to the visible character of the annual 

 displays. 



Light of the Night Sky. — Scientia of October i 

 contains an article by Prof. Charles Fabry on the 

 luminosity of the night sky. Prof. Fabry discusses 

 whether or not this luminosity can be attributed to 

 an unresolved background of faint stars. In this 

 connection he insists on the importance of concen- 

 trating attention on some small selected area and 

 determining how many stars of each magnitude are 

 present, with a view of extrapolation to stars below 

 the 2oth magnitude, which cannot be detected by 

 existing telescopes. The luminosity of the general 

 background of this area shouM be observed concur- 



IO8I 



rently. If, as appears probable, we cannot plausibly 

 attribute the general illumination to unresolved stars, 

 it would be natural to fall back on the hypothesis of 

 scattered light. That the light can be due to scatter- 

 ing by gaseous matter appears improbab'.e in view 

 of Lord Rayleigh's recent observations on the colour 

 and state of polarisation of the light of the night sky. 

 It may, however, be scattered by meteoritic matter. 

 The article concludes by reference to the aurora as 

 contributing in some cases to the light of the night 

 sky. 



Delineations of the Milky Way. — Dr. F.Goos, of 

 Hamburg University, has produced a useful series of 

 representations of the Milky Way as delineated by 

 various astronomers, partly from visual study and 

 partly from photographs. The work of Heis, Gould, 

 Easton, Boeddicker, and Houzeau has all been re- 

 duced by photography to a common scale, which is 

 somewhat small, but sufficient to show all the im- 

 portant features. There is also a new delineation 

 made by Dr. Goos himself from photographs by Prof. 

 Max Wolf, who contributes an introduction in which 

 he points out that photography is incomparably more 

 rapid and convenient than visual work, but that it 

 has difficulties of its own, as no lens covering a large 

 field will give images of the same character on all 

 parts of the plate; it is thus easy to draw fallacious 

 conclusions as to the relative brightness of different 

 regions. The exposures lasted from three to four 

 hours, and stars down to the thirteenth magnitude are 

 shown on the negatives. The reproductions were made 

 bv hand from the negatives and then reduced by 

 photographv. They show a large amount of com- 

 plicated structure, including many of the dark rifts 

 which may be due to opaque matter. Comparison 

 of the different authorities reveals many differences. 

 Boeddicker shows some faint outlying streamers, 

 which are absent from Houzeau and shorter and 

 fainter on the Wolf pictures. Dr. Goos suggests that 

 colour-differences may explain some of these dis- 

 cordances. 



NO. 2714, VOL. 



