February it, 1909] 



NA 7 URE 



439 



In No. 406 of the Observatory (p. loi, l-'ebruaryj Mr. 

 Evershed discusses the siime subject from the observations 

 made at the Kodall<anal Observatory. Dealing with the 

 water-vapour lines of intensity i or more given by Row- 

 land between A 5S50 and \ faooo, seventy in all, he finds 

 that thirteen are not shown on his plates, forty-two arc 

 absolutely unaffected, seven are weakened, and eight are 

 strengthened. Of the latter, four are only doubtfully 

 strengthened ; in two the strengthening is shown to be 

 due to close titanium companions, and two are decidedly 

 darkened. Mr. Evershed concludes that the weight of 

 evidence is against the probability of the existence of steam 

 in sun-spots, but, in commenting on this conclusion, Father 

 Cortic points out that the conditions of observation at 

 Stonyhurst and Kodaikanal were dissimilar, that the water- 

 vapour lines recorded as strengthened at both places still 

 have to be accounted for, and that the collateral evidence 

 from the laboratory must also be taken into account. 



Thk Spectrum and Form of Comet Morehouse. — The 

 Aslrophysical Journal for January (No. i, vol. xxix.) con- 

 tains three papers dealing with Morehouse's comet, 1908c. 

 In the first of these Prof. Frost and Mr. Parkhurst 

 describe and discuss two scries of spectrograms taken with 

 objective-prism or with slit spectrographs, respectively, at 

 the Yerkes Observatory. .As the scale of the spectra is in 

 each case very small, H0 to H9 covers about 3 mm., the 

 wave-lengths are only approximate, but comparisons with 

 the hydrogen lines in the spectrum of Vega, taken on the 

 same plate with the " slit " spectra, permitted the recog- 

 nition of several of the cometary condensations. 



The results differ from those previously published by 

 >I.M. Pluvinel and Baldet in that the Yerkes observers 

 find the third and fourth " carbon " (hydrocarbon?) bands, 

 whilst the Juvisy observers did not. .■\gain, the CN band 

 at \ 4216 could not be detected on the Yerkes spectro- 

 grams, whereas the Juvisy observers found that cyanogen 

 was fully represented ; both sets of observations agree on 

 the absence of continuous spectrum, but are not in agree- 

 ment in the matter of the wave-lengths of the bands. On 

 the other hand, the Yerkes wave-lengths agree with those 

 of MM. Deslandrcs and Bernard, but the latter were 

 unable to identify the " carbon " bands, and they found a 

 continuous spectrum on all their plates. 



.•\ study of the relative intensities of the spectra of the 

 head and of the streamers leads to some important results. 

 First, of the monochromatic images of the head, those at 

 AA 471 and 388 are strong, but no corresponding tail 

 images are shown, or are very weak, thus indicating that 

 the matter producing these radiations is mainly confined 

 to the comet's head. Again, the tails diverging at 

 different angles arc shown in the same monochromatic 

 images, thus indicating that they are composed of the 

 same materials. 



The second paper is by Prof. Barnard, and in it he 

 describes his latest photographs of the comet. The chanses 

 in form which occurred in the tail strengthen his belief 

 that the ejected matter met with resisting media, probably 

 meteor swarms, in space. 



Spectrograms, obtained with a slit spectrograph at the 

 T.ick Observatory, are described by Prof. Campbell and 

 Dr. S. Albrecht in the third paper. Thev recognise the 

 different edges of the third and fourth carbon and the 

 first and third cyanogen bands, but the second cyanogen 

 band is missing. Unknown lines at AA 3913, 4002, 4022, 

 42s.';' 4276. 4.';4Q, and 4570 are also shown on the spectro- 

 grams, and it is suggested that the last six may be related 

 bands, similar to those of cyanogen, due to some substance 

 as yet unknown terrestrially. 



Parallax of 23 H Camelopardalis. — From a photo- 

 graphic investigation, Herr Gustaf .Stromberg finds that 

 the parallax of 23 H Camelopardalis is t=-(-o"i27. 

 X = — "'■o'o, with probable errors of io"o53 and 

 + o'-057 respectively, where y is the relative correction 

 of the aberration constant. These values were obtained by 

 the measurement and discussion of twenty-eight plates 

 taken between October, 1004, and April, '1Q08, twenty- 

 three being employed for the estimation of the difference 

 in right ascension and twentv-five for that in declination 

 (Astronomische Nachrichten, No. 4295, p. 366). 



NO. 2050, VOL. 70] 



The Stars of the c and ac Subdivisions in the Maury 

 Spectral Classification. — In No. 4296 of the Astrono- 

 mische Nachrichtcn Herr E. Hertzsprung discusses the 

 distance, distribution, and probable general characteristics 

 of the stars which in Miss Maury's classification of the 

 " Spectra of Bright Stars " (Harvard) are placed in the 

 subdivisions c and ac. From the discussion of their proper 

 motions, parallaxes, &:c., the author finds, among other 

 conclusions, that these stars, among which many of the 

 brightest stars in the heavens are included, arc generally 

 at a greater distance and intrinsically brighter than those 

 of the other groups. 



The Stars surrounding 59 Cvgni. — No. 25 of the Con- 

 tributions from the Observatory of Columbia University 

 contains the measures of the Rutherfurd photographs of 

 stars surrounding 59 Cygni. The measures are discussed 

 by Prof. Jacoby, and in the final catalogue the positions 

 (1875-0), magnitudes, &c., are given for forty-six stars. 



Errors of Double-star Measures. — In Nos. 4298-9 of 

 the Astronomische Nachrichtcn (pp. 17-39, January 22) 

 Dr. H. E. Lau discusses the systematic errors of double- 

 star measures, and gives in detail the peculiar errors of 

 a large number of well-known observers. In each case a 

 brief note gives the mean probable error at different 

 distances and in position-angle ; the magnitude equation 

 of each observer is also discussed. 



ELECTRIFICATION OF RAILWAYS. 

 Present Position. 



SINCE the position of railway electrification was last 

 reviewed in these columns, a number of important 

 developments have taken place on the Continent and in 

 .\merica. In England the conversion of steam lines has 

 been slower than was anticipated. On the Continent, how- 

 ever, its spread has been quite as rapid as was expected 

 by any but the too optimistic. 



Electrification may be considered under practically the 

 same heads as railways themselves. That is to say, the 

 problem is quite different according to whether the appli- 

 cation be to main line, suburban, or purely urban traffic, 

 while the handling of goods traffic introduces an additional 

 consideration. 



.As regards the advantages of electricity for handling 

 urban traffic there is practically no longer any discussion. 

 Thus most of the purely urban systems in the great capitals 

 of the world, such as the tubes. District, and Metropolitan 

 Railways in London, the Metropolitan in Paris, the sub- 

 ways in New York, and the railways in Berlin and 

 Chicago, so far as they are self-contained, are now elec- 

 trically worked, steam where previously in use having 

 been replaced. 



As regards suburban lines, especially where this is 

 carried over lines which are also used for main-line traffic, 

 the process has not been carried so far. There are, of 

 course, plenty of instances where the conversion has taken 

 place both in the neighbourhood of great capitals and in 

 less populous districts. Thus in London the Harrow ex- 

 tension of the Metropolitan and portions of the Great 

 Western and South-Western now use electricity. In New 

 Y'ork the New York Central and the New York, New 

 Haven, and Hartford lines are now working electrically, 

 and the Pennsylvania tunnels are being rapidly equipped. 

 In Chicago the Illinois Central is now considering the 

 electrification of a large number of suburban lines, while 

 an extension of electric working to most of the suburban 

 lines in the Berlin district will probably take place before 

 long. In Melbourne the Railway Commissioners h.ave 

 recently had before them the whole question of converting 

 their suburban system, upwards of 200 miles, to electric 

 working. In London, however, the application of electric 

 working to the suburban sections of the great main lines 

 has made little progress. The Brighton Company has 

 been engaged for some years in converting a portion of its 

 suburban system between Victoria and London Bridge, and 

 the result of that experiment, both financially and technic- 

 ally, will doubtless have its result upon the other com- 

 panies. A trial trip was made a few days ago. 



