and Longitude of the Royal Obfervatory at G reenivich . 163 
3 °' 34 - / > 6 > or only T 4 -ths of a fecond lefs than by Dr* 
Bradley’s manufcript cited before. 
On my promotion to the Royal Obfervatory in 1765, finding 
its latitude to have been fo accurately fettled bv Dr. Bradley 
•' j 
before me, I might have thought myfelf difpenled from making 
any particular or very laborious obfervations for that purpofe ; 
however, I confirmed it by my own obfervations to great near- 
nefs, viz. within 1 or 2 // , at the fame time that J was eftablilh- 
ing a new catalogue of the principal fixed ftars, continually 
obferved here for fettling the right afcenfions of all other 
celeftial objects with the tranfit inftrument. The refult in 
brief is as follows. 
1 firft fettled the relative right afcenfions of about 30 of the 
brighteft fixed ftars, and lying neareft the equator, by a great 
number of obfervations with the tranfit inftrument, referring 
them to a, Aquilae as the fundamental ftar, whole right afcen- 
fton I alfumed from Dr. Bradley’s determination. Hence, 
by obferved tranfits of the fun and the fame ftars, in the fpring 
and autumn, when his daily motion in declination was at leaft 
1 6' or two- thirds of the greateft, I inferred the lun’s right afcen- 
fions relative to the right alcenfions of thole ftars fettled in the 
manner juft mentioned. Alfo from the lun’s obferved zenith 
diftances taken with the brafs mural quadrant on the fame days, 
and corrected by refradtion, parallax, and error of line of col- 
limation, with Dr. Bradley’s obliquity of the ecliptic, and 
latitude of the Obfervatory, I computed the fun’s declinations, 
and thence the right afcenlions correfponding to them. 
- Now, if the alfumed right afcenlion of a. Aquilas, and 
thence thofe of the other ftars were affedted with fome fmall 
error, as might be fuppofed, the fun’s right afcenfions deduced 
from the obferved tranfits w r ould differ the fame way from the 
Y 2 truth 
