Dec. 12, 1889] 



NATURE 



139 



perature curve." As I have previously pointed out, the "feebly 

 developed " stars of the group are probably either early or late 

 species, as the bands would be weak in either case. If it be an 

 early star, the bands in the blue will be most strongly deve- 

 loped ; while, if it be a late star of the group, the bands in the 

 red will be strongest. In the latter case, lines would probably 

 also be seen. 



(3) Konkoly classes this with stars of the solar type. As in 

 former stars of this class which have appeared in these columns, 

 observations are required to decide whether the star belongs to 

 Group III. or to Group V. (For criteria, see p. 20.) 



(4) This is a star of Group IV., of which observations of 

 the relative intensities of the hydrogen and metallic lines are 

 required, so that the star may be arranged in a line of tempera- 

 ture with others. 



(5) This is a star of Group VI., which Duner describes as 

 having a spectrum consisting of three zones, band 2 being prob- 

 ably also present. Particular attention should be given to the 

 intensity of the band 6 as compared with the others. Other 

 subsidiary bands should also be looked for, as they are seen in 

 several stars of lower magnitude, and it is important that we 

 should know whether their presence is dependent solely upon 

 the brightness of the star, or really indicates a difference in the 

 condition of the star itself. (For notation of bands, see p. 112.) 



(6) The maximum of this variable will occur on December 27. 

 The period is 315 days, and the magnitude varies from < I3'5 

 at minimum to 8"6 at maximum. The spectrum has not yet 

 been recorded. 



Note. — Some of the comets of which ephemerides have recently 

 appeared in Nature may possibly be bright enough for spec- 

 troscopic examination. It is not likely that, at their present 

 perihelion distances, their temperatures will be very high, so 

 suggestions for comparison spectra may be confined to those 

 suitable for low-temperature comets. The probable sequence 

 of spectra as a comet leaves aphelion is as follows: — (i) The 

 spectrum of a planetary nebula, as in the comets of 1866-67, 

 observed by Dr. Huggins. This consists of a single line in the 

 position of the chief nebula line near A 5CX5. (2) The low- 

 temperature spectrum of carbon, consisting chiefly of three 

 flutings near A 483, 519, and 561. (3) The high-temperature 

 spectrum of carbon, consisting mainly of flutings near A 564, 

 517, and a group of five flutings extending from 468 to 

 474. The most convenient comparison to begin with will be 

 the flame of a spirit-lamp, which will: give the hot carbon 

 spectrum. If this does not show coincidences with the comet- 

 ary bands, a comparison with the bright fluting in the spectrum 

 of burning magnesium should be made. This will determine 

 the presence or absence of the chief nebula line. If neither 

 shows coincidences, the positions of the bands relatively to the 

 hot carbon flutings may roughly indicate the presence or absence 

 of cool carbon. As the two less refrangible flutings of cool 

 carbon fall very near to two of hot carbon, the best criterion for 

 cool carbon is the fluting at A 483, which is about one-third of 

 the distance from the fluting commencing at 474 towards that 

 commencing near 517. Any variation ot the form of the least 

 refrangible cometary band from the corresponding carbon fluting 

 should be noted, as this varies with the temperature (see Ro)'. 

 Soc. Proc, vol. xlv. p. 168). A. Fowler. 



Photometric Intensity of Coronal Light. — The ob- 

 servations made by Prof. Thorpe during the solar eclipse of 1886 

 •(Phil. Trans., vol. clxxx., p. 363, 1889) show that the diminu- 

 tion in intensity of coronal light at different distances from the 

 sun's limb does not vary according to the law of inverse squares. 

 The following measurements make this apparent : — 



Distance in Solar Photometric Intensity. 



Semi-diameters. Observed. Law of Inverse Squares. 



16 ... o'o66 ... o'o66 



0*042 

 0029 

 0022 

 o'oi6 

 0013 



The brightness of the brightest measured part of the corona 

 (i "55 solar semi-diameters) was 200 times less bright than that 

 of the surface of the moon, or about 006 candle, whilst the 

 furthest spot at 3 '66 solar semi-diameters was only 1/800 of the 

 brightness, or 0015 candle. The results obtained will be useful 

 in comparing the brightness of the corona on this occasion with 

 that of other eclipses, and determining what connection the 

 sun-spot periods have with the coronal phenomena. 



Corona of January i, 1889. — Prof. Tacchini, in the Atti 

 del/a R. Accadcmia del Lined (p. 472), gives a note on the 

 corona as shown in a positive copy, on glass, of one of Mr. 

 Barnard's negatives taken during this eclipse. The corona ex- 

 tends, according to Prof. Tacchini, from -I- 64° to - 68° on the 

 west limb of the sun, and from -f 53° to -68° on the east limb, 

 these being about the limits of the zone of the maximum fre- 

 quency of protuberances derived from his own observations. 

 Two of the protuberances on the photograph were observed 

 at Rome and at Palermo. 



Minor Planet (12), Victoria. — Dr. Gill has issued the 

 ephemeris of this planet for the opposition of 1889, computed 

 from elements which have been corrected from the observations 

 of 1888. 



Observatories co-operating in the meridian observations of 

 Victoria should compare their results with this ephemeris, em- 

 ploying 8" -So for the solar parallax. 



Dr. Auwers has undertaken the discussion of the meridian 

 observations, so the detailed results should be forwarded to him 

 as soon as possible. 



Comet Swift (/ 1889, November 17). — The following 

 ephemeris is given by Dr. R. Schorr i^Asir. Nachr., No. 2937) : — 



The brightness of the comet =o-8i (December 12) and 0-57 

 (December 31), that at discovery being taken as unity. 



Coniptes rendns. No. 23 (December 2, 1889), contains obser- 

 vations of this comet extending from November 20 to Novem- 

 ber 27. It is noted that the comet is very feeble and diffuse. 



Periodic Comets. -^Several short-period comets return to 

 the sun in i8go, and their ephemerides will be furnished as soon 

 as issued. The perihelion passage of Brorsen's comet will 

 occur about February 25, Dennirg's comet may be expected to 

 return to perihelion in May, and D'Arrest's comet about the 

 third week in September. The orbit of Barnard's comet has not 

 jet been sufficiently defined to enable the date of perihelion 

 passage to be stated. 



The Eclipse Parties. — The following telegram relating to 

 the eclipi^.e parties has been received : — " Loanda, December 7. 

 — The United Stales corvette Pensaeola, Captain Arthur R. 

 Yates, with the Solar Eclipse Expedition on board, arrived at 

 St. Paul de Loanda to-day. The voyage down was very smooth, 

 with delightful sailing. The astronomers were at work on the 

 instruments all the way, and are all ready for the eclipse. The 

 time is now so short that it is inadvisable to attempt to take the 

 parly and all their instruments inland, so the Expedition will 

 locate at Cape Ledo immediately, and send one or two branch 

 parties inland, with such instruments as are not bulky or heavy, 

 and can quickly be set up and adjusted. The European eclipse^ 

 observers are beginning to arrive here. Mr. Taylor, of the 

 Royal Astronomical Society, London, has already arrived with 

 a small outfit of apparatus. None of the French or Germaiv. 

 astronomers are yet here. Cape Ledo turns out to be in every 

 way the most favourable point for locating the American Expe- 

 dition. Not only are the meteorological conditions likely to be 

 better, but the party can live for the most part on the Pensaeola, 

 as she will lie at a safe anchorage near the shore. The health 

 of the members of the party is thus insured. The eclipse is 

 several seconds longer there than at Muxima, and chances for 

 clear afternoon skits appear to be rather better. If nothing is 

 heard from the Expedition for the next few days, it may either 

 be taken that ihe Eclipse Station is finally located at Cape 

 Ledo, or that the semi-cannibal Quissamas have cleared out the 

 whole Expedition." 



RECENT INDIAN SURVEYS. 



'T^HE "Statement exhibiting the Moral and Material Pro- 

 ■^ gress and Condition of India," recently issued, devotes,, 

 as usual, a section to the survey work of the past year, oi 



