33i 
M. Struve’s Observations on Double Stars. 
In a work like this, we cannot find room for the ingenious 
analysis of La Place. We may merely remark, that the For- 
mulae which he deduces from the principle of least action, and 
that of Fermat, are found to be identical with the elegant For- 
mulae which Malus deduced from the construction of Huygens. 
D. B. 
Art. XXIII. — Observations on Double Stars. By M. Struve 
of Dorpat. (Continued from p. 109.) > 
The great degree of interest which is now attached to the 
accurate observation of the colour, magnitude, and relative po- 
sition of double stars, gives a particular value to the observa- 
tions of M. Struve. We shall, therefore, continue the series 
from the Correspondance Astronomique of Baron Zach ; and in 
the 3d volume of M. Struve’s observations, which have arrived 
in England, we may expect a continuation of his valuable ca- 
talogue. 
52. 1 Dragon. B. Asc. 17^^ 3'. N. Decl. 54° 43'. 
5th and 5th Mag. 
In 1819, M. Struve observed the difference of B. Asc. to bo 
= -f 0^/.242 ; the angle of position 60° 0' S. Free. ; and hence 
the distance was 4".19. By two projections he found it to be 
4". 5 and 3".7, the mean of which is 4".l 
Angle of position in 1781.7, rr 37° 38' HerscheL 
' 1803.1, — 50 2 Ditto. 
1819.7, — 60 0 Struve, 
53. Hercules. B. Asc. 17^ 6'. N. Decl. 14° 36'. 
4th and 7th Mag. 
This star is the finest double star in the heavens. The lar- 
gest is yellow, and the smallest blue. By 44 observations, M. 
* Those who have not an opportunity of consulting Sir William Herschel’s 
original papers on Double Stars in the Philosophical Transactions, will find the 
substance of them in the Edinburgh ENCYCtopiEDiA, vol. i. Art. Astronomy^ or in 
a more popular form, in the enlarged edition of Fergusori’s Astronomy, vol. ii. Ap- 
liendix.— Ed. 
