VOL. LXXII.] PHILOSOPHICAL TRANSACTIONS. 215 



tioned inaccurate, where an error amounting to 5° may possibly take, place. In 

 mere estimations of the angle, without any wires at all, an error may amount 

 to at least 10°, when the stars are near each other. 



6. The dates, when I first perceived the stars to be double, treble, &c. are 

 marked in the margin of each star. To shorten the work as much as possible, 

 I have put l for the large star; s for the small star; w for white; r for red; d 

 for dusky; n for north; s for south; and have also occasionally used other ab- 

 breviations that will be easily understood. It may be seen, that this catalogue 

 is yet in a very imperfect state, many of the stars not having even the principal 

 elements of distance and position determined with any degree of accuracy ; but 

 having already mentioned the reason why I give it imperfect as it is, I can only 

 add that my endeavours will not be wanting soon to remove those defects. How- 

 ever, since this can only be a work of some time, we may hope, in the mean 

 while, that many lovers of the science will turn their thoughts to the same 

 subject. 



CATALOGUE OF 



First Class. 



1. i Bootis. Flamst. 36. Ad dextrum femur in pe- 

 rizomate. 



Sept. 9, 1779- — Double. Very unequal. L red- 

 dish ; S blue, or rather a faint lilac. A very beautiful 

 object. The vacancy, or black division between them, 

 with 227 is | diameter of S; with 460, l\ diameter 

 of L; with 932, near 2 diameters of L; with 1159, 

 still further; with 2010, extremely distinct, 2j dia- 

 meters of L. These quantities are a mean of 2 years 

 observations. Position 31° 34' n preceding. 



2. I Ursae majoris. Fl. 53. In dextro posteriore 

 pede. 



May 2, 1780. — Double. A little unequal. Both 

 w and very bright. The interval with 222 is \ dia- 

 meter of L; with 227, 1 diameter of L; with 278, 

 near 1| diameter of L. Position 53° 47 ' S following. 



3. <r Coronae borealis, Fl. 17- 



Aug. 7. — Treble. The 2 nearest pretty unequal; 

 the 3d very faint with powers lower than 460. The 2 

 nearest both w ; the 3d d. Interval of the 2 nearest 

 with 227, full l| diameter of L; with 460, 2 dia- 

 meters of L. Position 77° 32' n preceding. Distance 

 of the 3d from L 24" by exact estimation. Position 

 25° n following by estimation. 



4. In constellatione Draconis, Fl. 16. 



Aug. 8. — Double. It is the star to which a line 

 drawn from » through fi>, points at nearly the same dis- 

 tance from /* as ^ from ». Considerably unequal. L 

 w; S w inclining to r. With 222, 1 diameter of L ; 

 with 278, U diameter of L. Position 24° 0' s fol- 

 lowing. There is a 3d star, at some distance, pre- 

 ceding. 



5. <r Cassiopeae, Fl. 8. In dextro cubito. 



Aug. 31 . — Double. It is the star at the vertex of a 

 telescopic isosceles triangle turned to the south. Very 

 unequal. L w a little inclining to r ; 6 d. With 222, 



DOUBLE STARS. 



near I diameter of L; with 460, 1| diameter of L. 

 Position 60° 28' n preceding. 



6". Quae infra oculum Lyncis, Fl. 1 2. 



Oct. 3. — A curious treble star. Two nearest pretty 

 unequal. Lw; S w inclining to rose colour. With 

 227, about \ diameter; with 460, full f diameter of 

 s. Position 88° 37' s preceding. The 1st and 3d con- 

 siderably unequal ; 2d and 3d pretty unequal. The 3d 

 paler. Distance from the 1st 9" 23"'; too difficult to 

 be extremely exact. Position with regard to the 1st 

 32° 33' n preceding. 



7. b Draconis, Fl. 39- Trium in recta, in prima 

 inflectione colli, borea. 



Oct. 3. — A minute double star. Extremely unequal, 

 the small star being a fine lucid point. L w; S in- 

 clining to r. With 227, 3 diameter of L ; with 460, 

 full lj diameter of L; with 932 (extremely fine) full 

 2 diameters of L. Position 77° 8' n following. A 3d 

 star at some distance ; dusky r. Position 6'3° 22' n 

 following. 



8. i Draconis, Fl. 6"3. In quadrilatero inflexionis 

 primae. 



Oct. 3. — A very minute double star. Excessively 

 unequal ; the small star can only be seen when the air 

 is perfectly clear. Lw; S d. With 227, less than 1 

 diameter of L ; with 278, not a diameter of L. Posi- 

 tion 63° 14' n preceding. A pretty large 3d star at 

 about 3 or 4'. Position of this 3d star with i 88° l& 

 n following. 



9. In cauda Lyncis media, Fl. 39- 



Nov. 24. — Double. Very unequal. L w ; S in- 

 clining to r. With 227, extremely close; with 460, 

 at least § diameter of S. A very fine object. Posi- 

 tion 25° 51' s preceding. A proper motion is sus- 

 pected in one of the stars. 



10. In sinistra anteriore pede Monocerotis, Fl. 11. 

 Feb. 15, 1781. — A curious treble star ; may appear 



double at first sight ; but with some attention we see 



