68 



NA TURE 



[May 15, 1890 



ployed ; but in place of them there are several broad dark bands 

 to which no origins have yet been assigned. Secchi first ob- 

 served the spectrum in 1869, and he pointed out that, if the 

 luminosity of the planet be due to solar light, it must undergo 

 great modifications in the atmosphere of the planet. Vogel and 

 Huggins re-observed the spectrum and mapped it in consider- 

 able detail, Vogel giving the positions of no less than twelve 

 bands. The five principal bands have the following positions : — 



618. Darkest part of a broad band, ill-defined towards the 

 red. 



596. Middle of a faint narrow band. 



573-8. Darkest part of a broad band. 



542'5. Middle of darkest band in spectrum. 



486T. Middle of a dark band. 



It has not yet been possible to explain any of the dark bands 

 by comparisons with known absorption spectra ; one band is 

 certainly coincident with the F line of the solar spectrum, but it 

 is much too broad to be due to reflected sunlight. Prof. Lockyer 

 gave his attention to the spectrum last year, and thought it pos- 

 sible that many of the apparent dark bands were simply contrast 

 appearances due to the presence of radiation flutings. At his 

 suggestion I examined the spectrum, and came to the conclusion 

 that he was right. I afterwards made observations, in conjunc- 

 tion with Mr. Taylor, with Mr. Common's 5 -foot reflector. A 

 full account of the results is given in Mr. Taylor's paper on the 

 subject {Monthly Notices, vol. xlix. p. 405). We decided in 

 favour of bright flutings, and Mr. Taylor afterwards mapped 

 them very carefully. The brightest fluting is near b, and it is 

 remarkable that Secchi noted this brightening in his light-curve 

 of the spectrum. Mr. Espin has since observed that the blue 

 end of the spectrum is broken up into bright bands and dull 

 shadings. If the apparent bright flutings are not contrast effects, 

 as has been suggested, the planet must be to a great extent self- 

 luminous. Dr. Huggins has since photographed the violet end 

 of the spectrum, and finds nothing but solar lines — a fact which 

 is very difficult to explain, when the remarkable character of the 

 visible spectrum is considered. 



It is highly important that further observations, by as many 

 ■different observers as possible, should be made. The apparent 

 diameter of the planet is so small that a Maclean spectroscope 

 shows the bands very well, but the brightnesses are best seen 

 when the spectrum is narrow, as is the case with bright-line 

 stars. 



(2) This nebula is thus described in the General Catalogue : 

 "Bright; large; extended in a direction 150°; pretty sud- 

 denly brighter in the middle to a resolvable nucleus." The 

 apparent size of the nebula, according to the Harvard College 

 observations, is 3' x i'. The spectrum has not been recorded. 



(3) This star is one of considerable interest. Duner says : 

 *' It appears to have a narrow band in the red, and a wide one 

 in the green. Perhaps III. a (Group II.), but by no means 

 III.^ (Group VI.)." It has been suggested, from a discussion 

 of the other members of the group, that the star is a represent- 

 ative of the very earliest stage of Group II., but further details 

 are necessary before it can be said with certainty. The con- 

 dition here should be almost c ometary, and hence, in further 

 observations, the bright flutings of carbon should be particularly 

 looked for. So far, this is the only observed star which may 

 possibly belong to the first species of the group. 



(4 and 5) These stars are ihcluded in Vogel's spectroscopic 

 •catalogue. The first is stated to be of the solar type, and the 

 second of Group IV. The usual observations are required in 

 each case. 



(6) This variable will reach a maximum about May 20. 

 The range is from 6-4-8-5 to 13 in 255-6 days. The spectrum 

 is one of Group II. (Duner), the bands being wide, but not 

 •very dark. The usual observations for bright lines and other 

 variations are suggested. A. Fovvi.eR; 



Changes in the Magnitudes of Stars. — At the April 

 meeting of the Royal Astronomical Society Mr. Isaac Roberts 

 presented a photograph of stars in the regions of Tycho Brahe's 

 Nova taken on January 12, with an exposure of 2 hours 55 

 minutes. D'Arrest charted the stars in the region of the Nova 

 in 1864 down to the i6th magnitude, and this chart has been 

 'Used by Mr. Roberts to compare with his photograph. He finds 

 no appearance of either a nebula or of a star on the photograph 

 in or about the position indicated by D'Arrest, but a comparison 

 of the chart and catalogue with the photograph shows that 

 -changes have taken place both in the positions and magnitudes of 



several of the stars since 1864. The changes particularized are 

 important when it is considered that they apply to less than half 

 a degree in right ascension, and one degree in declination. That 

 six of the stars shown on D'Arrest's chart and not shown on the 

 photograph, are absent on the latter on account of some physical 

 change having taken place in the stars, receives confirmation 

 from the fact that the photograph shows more than 400 stars on 

 a sky space where D'Arrest has charted only 212 stars. 



A Mechanical Theory ok the Solar Corona. — Prof. 

 Schaeberle of the Lick Observatory, has propounded an entirely 

 novel theory of the solar corona, a discussion of which will ap- 

 pear in the report of the eclipse of December 22, 1889. His 

 investigations seem to prove that the corona is caused Vjy light 

 emitted and reflected from streams of matter ejected from the sun 

 by forces which in general act along lines normal to the surface. 

 These forces are most active near the centre of each sun-spot 

 zone. Owing to the change of the position of the observer with 

 reference to the plane of the sun's equator, the perspective over- 

 lapping and interlacing of the two sets of streamers at these 

 zones causes the observed apparent change in the type of the 

 corona. To roughly test the theory Prof. Schaeberle has stuck 

 a lot of needles in a ball to represent the streams of matter, 

 placed the model in a beam of parallel rays, and allowed its 

 shadow to fall upon a screen, the result being that an infinite 

 variety of forms similar to the coronal structure can be reproduced 

 by simply revolving the model. It remains to be proved whether 

 a comparison of the forms that are seen according as the observer 

 is above, below, or in the plane of the sun's equator, agree with 

 those that should be seen on this theory. 



THE IRON AND STEEL INSTITUTE. 



"T^HE annual meeting of the Iron and Steel Institute was held 

 on Wednesday and Thursday of last week, in the theatre 

 of the Institution of Civil Engineers, the President, Sir James 

 Kitson, occupying the chair. There was a fair programme of 

 ten papers, and another was added after the list had been printed. 

 The following were the papers read : — ■ 



On a new form of Siemens furnace, arranged to recover 

 waste gases as well as waste heat, by Mr. John Head, London, 

 and M. p. Pouft", Nevers. 



Calculations concerning the possibility of regenerating the gas 

 in the new Siemens furnace, by Prof. Akerman, Stockholm. 



On the critical points of iron and steel, by M, F. Osmond, 

 Paris. 



On the carburization of iron by the diamond, by Prof. W. C. 

 Roberts-Austen, London. 



The changes in iron produced by thermal treatment, by Dr. 

 E. J. Ball, London. 



On the I\obert- Bessemer steel process, by Mr. F. Lynwood 

 Garrison, Philadelphia. 



Aluminium in carburetted iron, by Mr. W. J. Keep, Detroit. 



On certain chemical phenomena in the manufacture of steel, 

 by Mr. W. Galbraith, Chesterfield. 



The estimation of phosphorus in the basic Siemens steel bath, 

 by Mr. W. Galbraith, Chesterfield. 



On the Rollet process for producing purified castings, by Mr. 

 A, Rollet, St. Etienne. 



The first six of these papers were read and discussed at the 

 first day's sitting (Wednesday); and the remaining four were 

 disposed of before lunch-time on Thursday. It is seldom that 

 we have seen papers "rattled off" — the phrase most aptly 

 describes the procedure — in so rapid a manner. The members 

 who were present may certainly be congratulated upon having 

 got through a great many papers in a very short space of time ; 

 but it is a question whether there would not have been a gain 

 to knowledge had the discussions been of a somewhat more 

 deliberate nature. 



In addition to the above papers there was on the agenda a 

 memoir by Sir Plenry Roscoe, on the action of aluminium on 

 iron and steel. This, however, was not forthcoming ; a fact 

 which is to be regretted, as also is the cause which led to 

 it, the subject being one of considerable scientific and in- 

 dustrial importance at the present time, when the produc- 

 tion of aluminium is being so much cheapened, and such 

 great things are promised by those who advocate its use in the 

 metallurgy of iron and steel. Fortunately Mr. Keep's paper 

 was forthcoming, and this elicited a brief but useful discussion, 

 in the course of which Mr. James Riley, of the Steel Company of 



