42 Messrs Herschel and South on the Double Stars 



position was 43° 54' n/, and the distance 6".2.5. In 1824.21 

 the position was 50° 44' nfi and the distance 6".516. The 

 annual change in the angle is therefore — 0°.l 66. 



8. 31 Bode. Can. Min. R. A. 7^ 3r. Decl. N. 5° 43/ 

 The stars are excessively close, and nearly equal, being -/j 



Coronce in miniature, but smaller and much more difficult to 

 separate. They are of the 10th and lOg magnitude. A power 

 of 133 gives no suspicion of its being double, and 303 just se*- 

 parates their discs. In 1781, Nov. 28, the position was 27** 

 21' sf. In 1820.79 Struve made it 40° 46' n p, and the dis- 

 tance 1" or li". In 1823, Feb. 19, Mr South made the posi- 

 tion 37°.8, and since 1781 the angle has changed 10° yearly. 



9. ? Cancri, R, A. 8^ 2\ Decl. N. iW 11'. 



The stars are pretty unequal. Although beautifully defin- 

 ed and round, it is not to be seen triple. 



In 1781.89 its position was 88° 16' s p, and the distance 8". 

 In J802.ll it was 81° 47' sf. In 1820.29 Struve found it 

 71° 21', and in 1822.14 Messrs Herschel and South made it 

 68° IT sf, and the distance 6".24. This gives a mean annual 

 change of •— 0°.5813. " The change of position," says Messrs 

 Herschel and South, " has also been accompanied with a consi- 

 derable diminution of distance ; and farther observations must 

 decide whether this is the result of rectilinear or orbitual mo- 

 tion. If the former, the minimum of distance will be obtain- 

 ed in about forty years from the present time, and the change 

 during that period much less rapid than heretofore. On the 

 other hand, an orbitual motion will be indicated by the distance 

 continuing to diminish beyond that limit, and probably too by 

 an acceleration in the angular motion. A certain acceleration, 

 indeed, is already perceptible, 10° having been described in the 

 first twenty years, and 13^° in the last; but no great reliance 

 is to be placed on this, as the earlier measures depend solely on 

 single observations. Meanwhile the change remarked by Sir 

 W. Herschel in his paper of 1804 is fully confirmed, both by 

 M. Struve's observations and our own.""— PAiZ. Trans. 1824, 

 part iii. p. 115. 



