448 



JSfA TURE 



[March 12, 1896 



E. Lamp gives the following ephemeris for Berlin midnight 

 {Ast. Nach., 3338). 



Decl. Bright- 



o / ness. 



0-09 



R.A. 



h. m. s. 



March 12 ... 19 45 30 . . +5 12-8 

 14 ••• 45 o • •• 5 46-4 



16 ... 44 25 ... 6 20'2 .. 0"09 



18 ... 43 44 ••• 6 539 



20 ... 42 56 ... 7 277 ... o-o8 



22 ... 42 3 • •• 8 17 



24 ... 41 3 ■ •■ 8 357 ... o-o8 



26 ... 39 57 9 98 



28 ... 38 45 ... 9 440 ... 0-07 



30 ... 19 37 26 ... +10 i8-2 

 Comet Perrine-Lamp. — The revised elements of this comet, 

 which have been arrived at by Dr. Lamp, indicate the following 

 places for Berlin midnight {Ast. Nach., 3338) :— 



R.A. Decl. Bright- 



h. m. s. „ / ness. 



Marchi2 ... 3 i 59 ... +4834-4 ... 0-15 



14 ... 15 II 47 4i'2 ... 0-I2 



16 ... 26 9 ... 46 51-8 ... o-io 



18 ... 35 25 ... 46 6-5 ... o-o8 



20 ... 43 21 ... 45 25-4 ... 0-07 



22 ... 50 17 ... 44 47-9 ... o-o6 



24 ... 56 25 ... 44 i3'9 • • u'05 



26 ... 4 I 53 ... 43 431 ••• 0-04 



28 ... 6 51 ... 43 iS'i ••• 0-03 



30 ... 4 II 22 ... 42 49-4 ... 0-03 



The unit of brightness is that of February 157. On March 

 14 the comet will be nearly 2° south of a Persei. 



Orbit of 8 Cephei. — From an investigation of the dis- 

 placement of the lines in the spectrum of S Cephei, Dr. 

 Belopolsky came to the conclusion in 1894 that the light 

 changes of this short period variable are closely associated with 

 an orbital movement (Nature, vol. li. p. 282). The results 

 have been generally confirmed by another series of photographs 

 which were taken last year, but there are some differences in 

 the numerical data {Ast. Nach., 3338). For the velocity of the 

 system towards the sun the later value is 15 '2 English miles 

 per second, and the time of periastron passage is altered from 

 1-05 days after minimum to 0"9 days. The following data for 

 the construction of a curve of velocities of the bright star 

 relatively to the dark one, with which we must suppose it to be 

 associated, are derived from the figures given by Dr. Belopolsky : 



Interval from minimum Relative velocity 



in days. in Eng. mile.s per sec. 



0-8 +13-4 



0-5 ... + 7-8 



ID - 1-8 



1-5 ~ IO-6 



17 -""S 



2'0 - I2"9 



2-5 - IO-6 



3-0 - 6-5 



4'o + 1-4 



S-o + 8-3 



A + sign indicates a movement in a direction away from the 

 sun, and a - towards the sun. The period of revolution is 

 equal to that of the light changes, 5d. 9h. , and the maximum 

 occurs id. I5h. after the minimum. At the time of minimum 

 the stars lie very nearly along a line at right angles to the line of 

 sight, so that the reduction of light cannot be produced by an 

 eclipse. 



Attention is drawn to several notable differences in the 

 intensities of the lines in the star spectrum and in the spectrum 

 of the sun. Mr. Lockyer has also recognised such differences, 

 and has shown that the spectrum of S Cephei is practically 

 identical with that of 7 Cygni, a star of increasing temperature ; 

 four other variables of the 5 Cephei class have also been shown 

 to give a similar spectrum. 



The Absolute Velocity ok 61 Cygni. — The combined 

 results obtained for the proper motion of a star by meridian 

 observations, and for the velocity in the line of sight by the 

 spectroscopic method, enable the absolute velocity and direction 

 of movement to be determined. Dr. Belopolsky has recently 

 applied this to the brighter component of 61 Cygni, employing 

 the velocity derived from spectrum photographs taken at 



NO. 1376, VOL. 53] 



Pulkowa. The mean velocity in the line of .sight, corrected for 

 the earth's movement, and thus referred to the sun, is 337 

 English miles per second towards the solar system. Taking the 

 position of the apex of the sun's way as R.A. 267°, decl. +31°, 

 and supposing the velocity of the solar .system in space to be 9'3 

 English miles per second, the correction to be applied to 61 

 Cygni for the movement of the sun is 6 '9 miles per second. 

 Thus, the velocity of the star towards a fixed point in the 

 direction of the sun is 26*8 miles per second. 



Adopting a parallax and proper motion of o"'5 and 5""2 

 respectively, the linear velocity across the line of sight will be 

 30 miles per second, or, when freed from the velocity of the 

 solar system, 22-6 miles. The resultant absolute velocity is 

 accordingly 35 miles per second, the direction of movement 

 having a position angle of 61° and being inclined at an angle of 

 140° to the line of sight. 



ON THE APPEARANCE OF THE SPECTRAL 

 LINES OF CLEVFTE GAS IN STELLAR 

 SPECTRA. 

 TT is very rarely that so rapid progress is made as that which 

 -*- followed Prof. Ramsay's discovery of the line in the yellow, 

 corresponding with the solar line D3, in the spectrum of the ga.s 

 obtained from the mineral clevite. As early as May 9, Mr. 

 Lockyer communicated a paper to the Royal Society,^ in which 

 a table was given .showing that many of the unknown lines in 

 the stars with few lines in their spectra were really due to the 

 new gases. It seems to take some considerable time for English 

 work of this kind to get to Berlin, for on October 24 Prof. Vogel 

 made the same announcement to the Berlin Academy.'^ His 

 confirmation, therefore, is of great interest. 



It is not a little curious that the first star which he discusses 

 is not one of the stars in Orion to which Mr. Lockyer had 

 specially referred, but to ,8 Lyrse, which the same observer had 

 demonstrated a year or two ago to be a double star, the spectra 

 of the components resembling that of Rigel and Bellatrix. both 

 in Orion. 



Vogel found that a comparison of the lines of this star with 

 those in the spectrum of clevite gas showed in an unexpected 

 manner a great number of coincidences. 



His attention having been directed, in this perfectly inde- 

 pendent manner, to the question, he was led to examine the 

 spectra of many other stars, and to this end he employed the 

 rich material collected by Dr. Wilsing. In the communication 

 to the Academy, Prof. Vogel gives only a general survey of the 

 work, leaving a more detailed account for a later publication. 

 The first series of stars investigated were those in the constella- 

 tion of Orion, for there the fine A. 447 yu/* plays an important 

 part. The comparison, the results of which are here given in 

 tabular form, exhibited many coincidences ; the lines of clevite 

 gas most common to the stars &, 7, 5, €, C, A, r, Tr,, iTg, u> of 

 Orion were those of wave-length 382-0*, 388-9*, 402-6*, 

 414-4, 438-8, and 447-2*, those of helium being marked with 

 an asterisk. 



It was at first thought that, in consequence of the paucity of 

 stars of the Orion type in other parts of the heavens, few w ould 

 be found exhibiting the lines of clevite gas. An examination, 

 however, of 150 of the brighter stars of Class I. disclosed the 

 fact that no less than twenty-five, in which the characteristic 

 Orion lines, or, in other words, the lines of clevite gas, were 

 visible, were observed. 



Prof. Vogel informs us that until ihe spectra of all the stars of 

 Class I., down to about the 5th magnitude, have been obtained 

 and examined, an accurate idea of the distribution of these stars 

 in the sky cannot be formed. He further adds that a third part 

 of this work is already accomplished. Some of the stars in 

 which the lines in the clevite gas spectrum are well pronounced 

 are : 102 Herculis, 1 Herculis, a Virginis, 7 Pegasi, 8 Piscium, 

 8 Cephei, it Herculis, i Andromedje, t Herculis, C Draconis, tj 

 Leonis, p Pegasi, 8 Persei, 9j Auriga;. 



The above-mentioned investigation leads Prof. Vogel to form 

 the following deductions with regard to stellar classification. 

 These we give in full, remarking that while Dr. Vogel had pre- 

 viously classed the stars which now turn out to contain the 

 helium lines with stars like Sirius, Mr. Lockyer had classed 

 them apart-. 



1 P.R.S., vol. Iviii. p. 117. 



- Sitzungsberichte der Koaiglich-Pretissischen Akadciiiic dcr W'issen- 

 scha/ten zu Berlin, October 24, 1895. 



