78 Double Stars and the 
my examination by zones. All the stars extending to those 
of the eighth magnitude and even the most brilliant of the 
ninth, which could be detected by the finder of the instru- 
ments, were brought successively into the field of view, in 
order to examine which among them were double. As soon 
as a star was discovered to be double, its position was de- 
termined by reading the index of the two circles of the in- 
strument, as well as by the clock adjusted to sidereal-time ; 
and a short description of the star according to its class and 
magnitude was inscribed in the register. When the power 
of two hundred and fourteen times, commonly employed, 
induced a suspicion that a star was double, by exhibiting it 
of an elongated form 
table shows the increase of our knowledge relative to the 
double stars of these four classes, and of each of them in 
particular. 
Number of double Stars. 
es 
Ist class. 2d class. |B class. |4th class. 
n ew So Sy 987 6 "6 
In the catalogue of Herschell, 76 ae 
In the catalogue of 1820, 
_ The number of double stars is therefore nine times greater 
m this than in Herschell’s catalogue, and those of the first 
-_ Thave construc 
situated in the northe 
south of the equator, which will be published as an addition 
to the catalogue, a i i 
in general in those where there are the fewest stars; and ac- 
rdingly in the Great Bear, ina part of the Dragon, and in 
