82 Professor Struve on Double and Triple Stars, as 



which were already known. This catalogue includes 3063 

 double stars of the four first classes, of which 340 are found 

 in Herschers catalogues, and 440 in my catalogue of double 

 stars, known before 1820. 



The following table indicates the increase of our knowledge 

 of the double stars of the four classes, and of each of them in 

 particular. 



Number of double Stars- 1st to 4th Class. 1st Class. 2d Class. 3d Class. 4th Class. 



In the new catalogue, 3063 987 675 659 736 

 In the catalogue of 



Herschel, 340 76 76 82 106 



In the catalogue of 



1820, 441 96 112 111 122 



For six stars of the new catalogue the class has not been in- 

 dicated. The number of the double stars is thus nine times 

 greater in this catalogue than in that of Herschel, and that of 

 the stars of the first class thirteen times greater. 



I have made a map of the double stars now known situat- 

 ed in the northern hemisphere, and as far as five degrees south 

 of the equator, which will be published as an addition to the 

 catalogue of stars, in order that we may be able to judge of the 

 distribution of the double stars in the celestial vault. This 

 map proves that we find double stars in all the regions of the 

 heavens. But in general they are less numerous in those 

 places where there are fewest stars ; and hence it is that in the 

 Great Bear, in one part of the Dragon, and in the Canes Vena- 

 ticce, which are the constellations farthest from the Milky Way, 

 we find the least number of double stars. 



From this region the number of double stars increases in 

 general in proportion as we approach the Milky Way, that is 

 to say, in proportion as the number of stars increase. There 

 are, however, in the Milky Way itself, regions which are not 

 richer in double stars than the Great Bear ; such as that which 

 crosses Cepheus; thehonours of Frederick and Cassiopeia; those 

 more to the south, and upon the borders of the Milky Way ; 

 the region situated upon the constellation Pegasus, and the an- 

 terior part of that of Andromeda. The regions where they 

 are found in the greatest numbers are in Lyra, to the north of 



