386 Proceedings of the Royal Irish Academy. 



No. 563. 6 Seepentis. — 4 m. Sufi; 4-3 Heis and Argelancler ; 

 3-9 Gould (at Albany) ; and 4-2 at Cordoba. Smyth says, " There is 

 much uncertainty as to its magnitude. Ptolemy ranked it S in bright- 

 ness, and was followed by Ulugh Beigh, Lacaille, and Pigott ; Tycho 

 Brahe, Hevelius, Bayer, Plamsteed, Bradley, and De Zach made it of 

 the 3rd magnitude ; Piazzi and myself saw it constantly 4^ ; and 

 Montanari found it of the 5th. It must therefore be variable, and 

 should be carefully watched." In the Phil. Trans, for 1786, Pigott 

 remarks, with reference to this star, ' ' Montanari says he saw this star 

 of the 5th magnitude, and that the next year it grew bigger. I 

 examined it frequently in 1783, 1784, and 1785, and found it always 

 less than S Aquilse, equal to (i Aquilae and P. Ophiucii ; 4th magni- 

 tude." The Cordoba estimates vary from 4"1 to 4*6, and Dr. Grould 

 thinks there are strong indications of variability in one of the com- 

 ponents (Z7. A., p. 322). (Pranks 4^ and 5, July 29, 1877) ; 3-91 and 

 4-23 Pritchard (1882-472); 4-08 H.P. 



Gould gives the magnitudes of the components as 4'5 and 4'7 ; but 

 oil one occasion at Harvard College a difference of l"4m. was noted 

 {Observatory, Ajjril, 1883). 



August 22, 1876, I found 6 Serpentis slightly less than 77 Serpen- 

 tis ; October 21, 1876, 6 Serpentis considerably less than 8 Aquilae, 

 and but little superior to e Aquilae. 



No. 564. 11 AauiL^. — 5 m. Lalande ; 6^ Bessel ; 5*3 D.M. ; 

 5-0 Argelander and Heis ; 5-3 Gould (at Albany) ; and 5-8 at Cordoba. 

 Sir W. Herschel gives 11 , 10 and 18711j 10. Gould suspects 

 variation, although he includes the star in his " Standards of Magni- 

 tude " {U.A.,^. 32). 



In August, 1875, I estimated this star half a magnitude brighter 

 than 10 Aquilae; September 14, 1883, 11 at least one magnitude 

 brighter than 10; November 17, 1883, 11 about one magnitude 

 brighter tban 10, and four steps less than 18 Aquilae. These observa- 

 tions, compared with Sir W. Herschel' s, would seem to point to 10 

 Aquilae as the variable. 



No. 565. e AQiriLiE. — 3 m. Tycho Brahe ; 4 Hevelius ; 4 and 3^ 

 Lalande; 4 Harding; 3*77 Sir J. Herschel ; 4 Heis ; 3-86 Pritchard 

 (1882"583). Suspected of variation by Sir "W. Herschel, who says 

 {Phil. Trans., 1796), "13 Aquarii (e) September 3, 1784. It is not 

 much larger than either 11, 18, or 19, so that we may be pretty 

 certain it must have lost some of its lustre since the time of Plamsteed. 

 In his observations it is marked 4 m." June 20, 1879, Franks found 

 it nearly two magnitudes less than t, Aquilae, and equal to 1 1 1 Hercu- 

 lis ; September 12, 1879, e alittle brighter than 110 and 111 Herculis ; 

 "certainly brighter than on June 20" {private letter). In August, 

 1875, I found e about 4^ m., and very little, if anything, brighter 

 than 111 Herculis. 4-10''and 4-3 H.P. 



