VOL. XXXV. J PHILOSOPHICAL TRANSACTIONS. 311 



made with Mr. Molyneux's, was no small inducement to him; but the chief of 

 all was, the opportunity he should thereby have of trying, in what manner 

 other stars were affected by the same cause, whatever it was. For Mr. Moly- 

 neux's instrument being originally designed for observing y Draconis, ih order, 

 as before said, to try whether it had any sensible parallax, it was so contrived, 

 as to be capable of but little alteration in its direction, not above 7 or 8 mi- 

 nutes of a degree, and there being few stars within half that distance from the 

 zenith of Kew, bright enough to be well observed, he could not, with his in- 

 strument, thoroughly examine how this cause affected stars differently situated 

 with respect to the equinoctial and solstitial points of the ecliptic. 



These considerations determined him; and by the contrivance and direction 

 of the same ingenious person, Mr. Graham, his instrument was fixed up 

 August IQ, 1727. As Mr. B. had no convenient place where he could use so 

 long a telescope as Mr. Molyneux's, he contented himself with one of but 

 little more than half the length of his, viz. of about 12-1- feet, his being 24J-, 

 judging from the experience which he already had, that this radius would be 

 long enough to adjust the instrument to a sufficient degree of exactness ; and 

 he has had no reason since to change his opinion ; for from all the trials he has 

 yet made, he is well satisfied, that when it is carefully rectified, its situation 

 may be securely depended on to half a second. As the place where the instru- 

 ment was to be hung, in some measure determined its radius, so did it also the 

 length of the arch, or limb, on which the divisions were made to adjust it; 

 for the arch could not conveniently be extended farther, than to reach to about 

 Si" on each side the zenith. This indeed was sufficient, since it gave an oppor- 

 tunity of making choice of several stars, very different both in magnitude and 

 situation; there being more than 20D inserted in the British catalogue, that may 

 be observed with it. Mr. B. needed not to have extended the limb so far, but 

 that he was willing to take in Capella, the only star of the first magnitude that 

 came so near his zenith. 



The instrument being fixed, Mr. B. immediately began to observe such stars 

 as he judged most proper to give light into the cause of the motion beforemen- 

 tioned. There was variety enough of small ones; and not less than 12 that 

 he could observe through all the seasons of the year; these being bright enough 

 to be seen in the day-time, when nearest the sun. Mr. B. had not been long 

 observing, before he perceived that the notion they had before entertained of 

 the stars being farthest north and south, when the sun was about the equinoxes, 

 was only true of those that were near the solstitial colure; and after having 

 continued his observations a few months, he discovered, what he then appre- 

 hended to be a general law, observed by all the stars, viz. that each of them 



