I 



15. 1888] 



NATURE 



57 



motion, prove their systemic connection (" Obs. de 

 || Poulkova," ix. 106). 



*' The remaining stars on our list are relatively fixed. 



2 2344.— Magnitudes 8*5 and 10 when first measured 



by Struve ; 85 and 12 in 1829, distance = i""38. The 



oinpanion was not again seen until 1835 (" Mens. 



rom.," pp. 37, 296). The instability of its light was 



ler attested by its invisibility to Secchi in 1859, to 



-elmann in 1865 (Engelmann, Astr. Nach., No. 1674). 



2 2718. — Components intrinsically equal, but by turns 



^.lightly superior. Period of change probably short 



i (Struve, " Mens. Microm," p. 142). 

 61 Geminorum. — The brighter component varies from 

 6 to 7" 5 magnitude, the fainter from 9 to seeming 

 extinction (Flammarion, " Les Etoiles," p. 320). The 

 larger star, which is of a deep yellow colour, was re- 

 corded by Piazzi as of 7'8, by Heis and Argelander as 

 I of sixth magnitude (N.\TURE,xii. 27 ; " Harvard Annals," 

 I xiv. 445). It was photometrically determined at Harvard 

 I as of 57 magnitude. Its attendant eluded Webb's search 

 ' in 1855, Knott's in 1861 and 1871, but was recovered in 

 tSt;, when of I2"5 magnitude, by H. Sadler, using a 

 nch Calver's reflector (Smyth, " Cycle," p. 202 ; Webb, 

 ular Science Review, xiv. 309). Since these stars are 

 apart, the probability of their physical connection 

 re^ts chiefly upon their agreement in exhibiting marked 

 tluctuations of light. 



p (5) Ophiuchi, described by Admiral Smyth as of 5 

 and 7-5 magnitudes at 4" ; yellow andblue colours (" Cycle," 

 p. 457). But Herschel at the Cape, 1834-37, and Jacob at 

 . Madras, 1846, found them exactly equal. Herschel and 

 I South in 1824, Secchi in 1856-57, give a difference of one 

 ' magnitude. Main called them 4 and 4-3, and they were 

 i measured at Harvard as 5*3 and 6 magnitudes (Sadler, 

 i Astronomical Register, xvii. 73; Pickering, "Annals," 

 1 xiv. 461). 



\ Scorpii is No. 489 of Gore's " Suspected Variables." 

 F. Struve assigned to the components magnitudes 2 and 

 4; Pickering, 3 and 5-2, combined, 2*9. J. Herschel 

 found a difference of only one magnitude, Webb of 3^, 

 Gore of 2h magnitudes (Webb, " Celestial Objects," p. 

 386 ; see "also Nature, vol. xxiii. 206, 362). Their 

 colours are yellowish-white and lilac, or (according to 

 Dembowski) ashy green, and they belong to the first 

 spectroscopic class. They are separated by an interval 

 of 14", but Burnham detected in 1881 a close, faint 

 attendant upon the principal star (Memoirs R. A. Society, 

 xlvii. 193). 



6 Serpentis = 2 2417. — The components are 2i"'6 

 apart, and relatively fixed. Both emit yellowish-white 

 light marked by the Sirian quality of absorption. They 

 were together ranked by Tycho and Bayer as of third 

 magnitude, by Montanari as of fifth, but, with noticeable 

 1 subsequent brightening (J. Cassini, " ^Idmens d'Astr.," 

 p. 74). Gould's estimates wavered from 4'i to 4'6 mag- 

 nitude, and gave strong evidence of variability in one of 

 the stars (" Uranometria Argentina," p. 322). Gore 

 thinks that its changes may prove to be modelled on 

 those of Algol (Journ. Liverpool Astr. Soc, v. no). The 

 separate photometric magnitudes registered at Oxford 

 were 39 and 4*2 ; at Harvard, 47 and 5"i, where, how- 

 ever, the difference of lustre between the stars was 

 perceived, in 1878, to fluctuate from 034 to r69 mag- 

 nitude ("Harvard Annals," xi. 136, xiv. 463). Dundr 

 considered the principal star to be steadily of 4, the 

 companion to vary from 42 to 47 magnitude (" Mdsures 

 Microm.," 1876, p. 112). 



2 1875 is composed of two white stars at 3"'2, the pre- 

 '[•ceding of about ninth, the following varying from 8*5 to 

 tenth magnitude. Dundr had no doubt of the real. ly of 

 :hese changes (" Mdsures Microm.," p. 70 ; Struve, " Mens. 

 ; Microm," p. 73). 



Atlas Pleiadum = 2 453.— Found double at o"79 by 

 Struve in 1827, doubtfully "wedged" in 1830, single 



with a power of 800 in a clear sky in 1836 (" Mens 

 Microm.," p. 283). As single it has been seen by every sub- 

 sequent observer, including Burnham, who at intervals 

 during five years searched vainly for the companion 

 detected and always fully believed in by Struve (Mems. 

 R. A. Soc-, xliv. 230). But during the passage of the moon 

 across the Pleiades, January 6, 1876, Hartwig recorded 

 the immersion of Atlas as non-instantaneous, a faint 

 remnant surviving the chief part of the light for six-tenths 

 of a second. He did not then know that the star had 

 been marked at Pulkowa " duplex difficillima " (Winnecke, 

 Astr. Nach., No. 2074). 



72 Ophiuchi = 02342 is a somewhat similar example. 

 .\n eighth magnitude companion at i"5 was discovered 

 by O. Struve in 1842, but could rarely afterwards be seen, 

 and excited vehement suspicions of pronounced varia- 

 bility (•' Pulkowa Catalogue," No. 342). It was last 

 observed at Pulkowa in 1876, and never elsewhere than 

 at Pulkowa except once by Father Secchi at Rome in 

 August 1859 (Nature, vol. xvi. p. 194). Newcombcould 

 find no trace of it with the Washington 26-inch on two 

 exceptionally fine nights in 1874, nor Hall in 1876. Burn- 

 ham was equally unsuccessful, and after much fruitless 

 scrutiny recorded the star as "certainly single" in a 

 "first-class night" of August 1880 (Mems. R. A. Soc, 

 xliv. 276). Its spectrum, like that of Atlas in the Pleiades, 

 is conspicuously of the first type. 



/3 Cygni was found by Klein variable from 3-3 to 3-9 

 magnitude in 1862-63 {Astr. Nach., No. 1663). Espin 

 holds this star to belong to a distinct class of variables 

 (exemplified by 63 Cygni) which change less than one 

 magnitude in a period of several years {Monthly Notices, 

 xliii. 271). Webb and Gemmill agreed, in 1881-82, in 

 finding ji Cygni much waned from its former brightness 

 {Astr. Reg., xx. 14, 46). The magnitudes of its com- 

 ponents were determined at Harvard as yi and 5*2 — 

 conjointly, 3. Their photometric difference, however, 

 appeared, from Oxford measures of November 6, 1882, 

 to be only r82 magnitude {Monthly Notices, x\ii\. 102). 

 Although 34" apart, and immovable, their physical 

 union is decisively affirmed by the splendid contrast of 

 their golden and azure tints, to which complementary 

 absorption-spectra correspond (Huggins, Phil. Trans., 

 chv. 431). 



8 Cephei forms, with a " caerulean blue," seventh mag- 

 nitude companion at 41", a pair resembling ^ Cygni 

 (Webb, "Celestial Objects," p. 270). The large star 

 varies regularly from 37 to 4*9 magnitude in 5d. 8h. 48m. 

 The maximum of May 6, 1868, was, however, stated by 

 Schmidt to have been barely indicated {Astr. Nach., No. 

 1745). A minute attendant at 19" was discovered by Burn- 

 ham in 1880. The spectrum of the variable is of the 

 solar type. It has virtually no proper motion. 



a Herculis = 2 2140 was divided by Maskelyne, 

 August 7, 1777. The variability of the primary, dis- 

 covered by Herschel in 1795, ranges from 3*1 to 3*9 mag- 

 nitude in a period fluctuating between 26 and 103 days 

 (Gore's " Variables," N o. 1 29). The attendant is generally 

 rated at the sixth, but Struve found it to change from fifth 

 to seventh magnitude (" Mens. Microm.," p. 97). The 

 colours of the pair are vividly contrasted orange and 

 emerald. The large star shows a magnificent banded 

 spectrum of 1 1 1. a type ; the smaller, one analogous to that 

 of the companion of ^ Cygni in having its absorption 

 almost wholly below the green (Huggins, Phil. Trans., 

 cliv. 432). The common proper motion of the pair carries 

 them in a century over a space nearly equal to the interval 

 separating them (4"*5). 



h 1470 = Lalande 38428.— -Both stars are supposed 

 to be variable, but have been little observed. Secchi 

 estimated them of 7 and 8 magnitudes in 1856, and 

 measured their distance at 23"'8. Physical relationship 

 is indicated by their " superb " coloration in red and 

 blue (" Catalogo di 1321 Stelle Doppie," p. 117; Webb 



