CATALOGUE OF BINARY STARS. 209 



evident from Mr. Knott^s measures in 1865 that the star 

 has changed its angle of position 34 degrees, and in dis- 

 tance '65" in 22 years, and, consequently, must be added 

 to the list of binaries. 



P. III. 98, 145 Leonis, 17 Orionis, and some others are 

 inserted on the authority of only two observers ; but they 

 appear to be binary systems, and deserve attention. 



Since the date of the ' Cycle' the number of binary stars 

 has been greatly increased; and several observers have 

 favoured me with the names of stars which have changed 

 their angles of position sufficiently to entitle them to a 

 place amongst that class of objects; and they are accord- 

 ingly inserted. 



To the gentlemen referred to I take this opportunity of 

 returning my best thanks. 



With few exceptions, I have not included in this cata- 

 logue any object which has shown a change of position of 

 less than 10 degrees in 30 years. There are many stars 

 which may eventually prove to be binary ; but their motions 

 are extremely slow, and require examination at long inter- 

 vals. Of the few stars forming the exception to the 

 rule adopted, I may name Sirius, Antares, and a few others 

 as interesting objects, and deserving close attention on the 

 part of those observers who have telescopes of sufficient 

 aperture to measure the angles of position and distances of 

 such difficult objects. 



D. 5 and A. C. 5 refer respectively to the lists of double 

 stars discovered by Mr. Dawes and Alvan Clark. 



I do not attach any importance to my own measures ; 

 and the following are given merely to show that the work 

 done with a telescope of 5 inches aperture may be useful 

 in this department of astronomy, and that the possessors of 

 such, and even smaller telescopes, may do good work by 

 taking advantage of favourable states of the atmosphere. 



SER. III. VOL. III. p 



