and Longitude of the Royal Obfervatory at Greenwich. 17- 
before mentioned zenith diftances of 14 ftars, obferved at Green- 
wich by Dr. Bradley and by the Abbe de la Caille at 
the College of Mazarine at Paris, with the eftablifhed latitudes 
of the two Obfervatories, nearly ; in doing which I (hall claim 
the fame right to correct Dr. Bradley’s oblervations by his 
table of refractions, as I have allowed the Abbe de la Caills 
to be intitled to correct his obfervations by his table of refrac- 
tions j which, I think, will be allowed me, after what 1 have 
faid of the manner in which the Greenwich refractions were 
deduced and the inftruments made ufe of. The difference ot 
latitude of the College of Mazarine and the Royal Obfervatory 
at Greenwich will then come out by the feveral ftars, as fol- 
lows; 2° 3 f 1 2", 7, i6",o, 1 3", 8, 1 3", 7, 1 8 // , 4 , 1 7" 7, 
1 2 5 1 1 /7 ,9» 
19 > 7 > 
23^,2, 
*7 > 7 > l 7 
l 3"*9i 
The mean is 2 0 37' 1 5", 2 (or 8^,7 lefs than the Abbe de la 
Caille’s refult in his method of calculation, which I have 
ftiewn to be inadmiffible) and added to 48° $ i' 29", 3 ,the latitude 
of the Abbe de la Caille’s Obfervatory gives 5C 28' 44", 5 
for the latitude of the Royal Obfervatory at Greenwich, only 
4"! more than eftablifhed by Dr. Bradley’s obfervations 
and my own ; a fufficient agreement, efpecially confidering 
that many of the ftars were at great diftances from the zenith, 
and that no account has been made of the temperature of the air 
at the times of the obfervations. The proper method, however, 
of fettling the difference of latitude of two Obfervatories is by 
ftars near the zenith, as I obferved before ; and the difference of 
the latitudes of the two Obfervatories of the College of Maza- 
rine and Greenwich, by the Abbe de la Caille’s obferva^- 
tionsof (3 and y Draconis compared with mine, was 2° 3 7' 10 /7 , 4, 
and compared with Dr. Bradley’s 2 0 37' 10", 7, the firft of 
which, added to the Abbe de la Caille’s latitude, gives, 
5 ^ 
