CONTENTS. 



Art. I. On Double Stars. By M. Abago, - - Page 1 



1. What is to be understood by Double Stars ? - ib. 



2. Why is it that these Double . Stars have suddenly be- 



come an object of 'such as.siduous attention ? - 5 



3. The consequences Mrhich-r^ultr from the nature of the 



motions which are observed in the Double Stars. 

 And first, as they relate to the universality of the 

 Newtonian attraction, - - - - 11 



4. When the distances of the Double Stars from the 



Earth shall have been determined, then the masses 

 of those of the Stars whose relative motions are 

 known, may be easily compared with the mass of 

 the Earth or Sun, - - - - 12 



5. The Observations upon the Binary Groups, composed 



of independent Stars, may serve to determine the 

 distance from the Earth of one of the Stars of 

 which these Groups are composed, - - 20 



6. The observations of Double Stars, properly so called, 



may serve one day to determine either the distances 

 of these .binary groups from the Earth, or to fix a 

 maximum or minimum limit beyond which they can- 

 not be placed, - - - . . 27 



7. Concerning the Colours observed in the Multiple Stars, 33 



8. The Double Stars have become a means whereby we 



may judge of the excellence of Telescopes, - 37 



9. Of the part which the doctrine of Probabilities has ful- 



filled in the question of Double Stars, - - 39 



