Mar., 1905.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



63 



ASTRONOMICAL. 



The R^ecent La.rge Sun-Spot. 



On the ^Sth of January a dark streak appeared on the sun's 

 eastern limb, which from its length, and the very extensive 

 masses of bright faculas surrounding it, gave promise of an 

 unusually large disturbance. On Monday morning, the 30th of 

 January, renewed observations showed that the spot was the 

 largest of any seen during the present increase of activity, and 

 in fact may have been equal to the great spot of February, 

 1894. 



By means of suitable smoked or coloured glasses it was quite 

 easy to see the dark area of the spot on the sun's surface with 

 the naked eye. Observations with telescopic aid of varying 

 powers showed the umbra or dark centre of the spot to be 

 split up into several portions by intensely bright streaks or 

 '• bridges," and these were found to be constantly changing as 

 the sun was seen day after day. Towards the latter part of 

 its visibility numerous small umbrae were developed on the 

 following side of the main spot, this being a very common 

 feature of sun-spot evolution. 



In accordance with the time of the sun's rotation, 25'38 days, 

 the spot reached and passed round the sun's western limb on 

 the loth of February, its path across the disc having had about 

 a mean southerly latitude of 16°. At its greatest development 

 the diameter of penumbra was about 2' of arc = about 

 53,000 miles The spectroscopic observations of the spot have 

 been most interesting and instructive. As might have been 

 anticipated from the rapid changes in the telescopic form of 

 the spot, the spectrum lines were observed to be considerably 

 distorted both to the red and violet sides, indicating strong 

 vortical disturbances to be existent in the spot area. 

 Frequently many of the special lines which are known to 

 be distinctive of spot spectra were seen to be bright, or 

 reversed, in comparison with the dark Fraunhofer lines. These 

 special lines, dark or bright, were identical with those observed 

 generally in spot spectra, and consisted chiefly of very faint 

 lines of the rare elements vanadium, scandium, titanium, and 

 some unknown element or elements. 



Detailed accounts of magnetic measurements are not yet to 

 hind, but it is announced that on Friday, February 3, the 

 magnets at Greenwich Observatory were disturbed about 

 1.30 a.m., the effect showing throughout the day. Reaching a 

 maximum value towards midnight, the oscillation died away 

 on the morning of the 4th of February, about S.o a.m. It may 

 be noted that the large spot was near the central meridian of 

 the sun's visible hemisphere about the time of the magnetic 

 disturbance. 



» » « 



Jupiter's Sixth SaLtellite. 



Shortly after the telegram from Professor Perrine announc- 

 ing his discover)- of a sixth satellite, there came an interesting 

 despatch from Professor Wolf, stating that one of the minor 

 planets photographed by him was very near to Jupiter, and 

 suggesting that this might be the suspected satellite observed 

 by Perrine. The following data give the co-ordinates of this 

 new asteroid, 1905 P.V. : — 



R.A. = ih. 31m. 5gs. ^ Jan. 23d. yh. S'Sm. Koenigstuhl mean 

 Decl. = -f 8= 36' 13" ) time. 



Daily motion in R.A. = -f- 23' ; daily motion in Decl. = — g'. 



The day after, however. Professor Perrine sent a further 

 telegram, giving a new position for the satellite, and definitely 

 stating that the object discovered at the Lick Observatory is 

 not identical with the minor planet 1905 P.V. photographed by 

 Professor Wolf. This new position of the satellite was : — 

 K.A. = ih. 2im. 8s. I , j ou /r • 1 ^- s 



Decl. = -1-7° 27' I January i7d.Sh. 44-3 (Lick meantime). 



Obervations on the 17th of January gave the following co-or- 

 dinates of position of the satellite with respect to Jupiter : — 

 Distance (t-) = 36' > . , ,„ _ 



Position angle (6) = 266^ i' January i7702d. (G.M.T.) 



* * * 



New Form of Hydrogen in Stellar Spectra. 



Hydrogen is well known to be present in the spectra of 

 most of the stars which have hitherto been spcctroscopically 

 examined, the spectrum usually shown being that consisting 

 of a rhythmical series of lines whose wave lengths are con- 

 nected by Balmer's law. In November, 1896, Profes.sor 

 Pickering announced that on the photographs of stellar spectra 

 obtained with the Draper Memorial telescope there had been 

 found a star which showed a new series of rhythmical lines in 

 addition to the ordinary hydrogen series. Subsequent dis- 

 cussion of their wave lengths elicited the important fact that 

 they were undoubtedly due also to hydrogen, but indicated 

 conditions of temperature and pressure hitherto unknown. 

 This star was f Piippis, which, having a southerly declination 

 of 39° 43', was unfortunately inaccessible to the astronomers 

 of northern latitudes. Quite recently, however. Professor 

 Pickering has been able to announce that by examination of 

 later photographs of stellar spectra it has been discovered 

 that the star \ Cephci has a spectrum identical with that 

 of s" Piippis, and as this star, of declination -j- 5S- 56', attains a 

 considerable altitude in northern latitudes, the instruments of 

 European observatories will be available for its examination. 

 It is somewhat unfortunate that it is a much fainter stir 

 than s" Piippis, its magnitude being about 5-6, but with the 

 large prismatic cameras which are now installed at many 

 observatories this will not prove a serious drawback to its 

 being observed. 



* * * 



Ephemeris for Observations of Comet 

 1904 d. 



(120 midnight, Berlin Mean Time.) 



The following positions have been computed by Ebell at 

 Kiel Centralstellc : — 



Brightness in terras of that en 1904, Dec. 17 



BOTANICAL. 



By S. A. Sk.\n. 



Several plants of more than ordinary interest are figured and 

 described in the last part of " Hooker's Icones Plantarum." 

 Thiseltnnia, a little plant with narrow leaves and small white 

 flower -heads, belonging to the Aski- family (Composita;), and 

 Efichsciiia, a leguminous plant, with yellow, purple-striped 

 flowers, are two new generic types discovered, in addition to 

 several new species, by Mr. G. H. Thiselton-Dyer in West 

 Australia. On plate 2785 is depicted the Chinese representa- 

 tive of the genus Liriodcndvon. Formerly it was regarded as 

 a variety of the well-known Tulip Tree of eastern North 

 America, which it very closely resembles. It seems extra 



