VOL. XXXV.] PHILOSOPHICAL TKANSACTIONS. 317 



sensibly difFerent in such stars as seem near together, though they appear of 

 very dift'erent magnitudes. And whatever their situations are, if we proceed 

 according to the foregoing hypothesis, the same velocity of light is found from 

 his observations of small stars of the 3th or 6th, as from those of the 2d and 

 3d magnitude, which in all probability are placed at very difFerent distances from 

 us. The small star, for example, before noticed, almost opposite to y Draconis, 

 being the 35th Camelopard. Hevelii in Mr. Flamsteed's catalogue, was 19" 

 more northerly about the beginning of March, than in September. Whence 

 Mr. B. concludes, according to his hypothesis, that the diameter of the little 

 circle described by a star in the pole of the ecliptic, would be 40".2. 



The last star of the great Bear's-tail of the 2d magnitude, marked n by Bayer, 

 was 36" more southerly about the middle of January than in July. Hence the 

 maximum, or greatest alteration of declination of a star in the pole of the 

 ecliptic, would be 40".4, exactly the same as was before found from the obser- 

 vations of y Draconis. 



The star of the 5th magnitude in the head of Perseus, marked t by Bayer, 

 was 25" more northerly about the end of December, than on the 29th of 

 July following. Hence the maximum would be 41". This star is not bright 

 enough to be seen as it passes over the zenith about the end of June, when it 

 should be according to the hypothesis farthest south. But because we can more 

 certainly depend on the greatest alteration of declination of those stars, which 

 have been frequently observed about the times when they become stationary, 

 with respect to the motion now considered ; Mr. B. set down a iew more in- 

 stances of such, from which we may be able to judge how near it may be possi 

 ble, from these observations, to determine with what velocity light is pro- 

 pagated. 



a Persei Bayero was 23" more northerly at the beginning of January, than in 

 July. Hence the maximum would be 40".2. a Cassiopeae was 34" more 

 northerly about the end of December, than in June. Hence the maximum 

 would be 40".8. |3 Draconis was 39" more northerly in the beginning of 

 September, than in March; hence the maximum would be 40". 2. Capella was 

 about 16" more southerly in August than in February ; hence the maximum 

 would be about 40". But this star being farther from the zenith than those be- 

 fore used, he cannot so well depend on the observations of it, as of the others ; 

 because he meets with some small alterations of its declination, that do not 

 seem to proceed from the cause now considered. 



Mr. B. compared the observations of several other stars, and they ail con- 

 spire to prove that the maximum is about 40" or 41". He therefore supposes it 

 is 40-i-", or, which amounts to the same, that light moves, or is propagated, as 



