C r 53 ] 
whereas the latter increafes it to near 10" L\ the dif- 
ference is too confiderable not to deferve an enquiry 
into its caufes. The expected volume is at lad come 
to hand ; and my firfl care has been to examine with 
the in od fcrupulous attention the obfervation made at 
the Cape. I owe this testimony to truth, that this 
obfervation, as well as all the others of Me IT. Maion 
and Dixon, appears to me to have been made with 
great judgment. An exception might however be 
made as to the extenfive delcription of an appulfe ot 
cr Sagittarii to the Moon’s, fouthern limb, which is 
found page 389. This certainly was moie than 
an appulle, and the dar was really immerged at 
the Cape. 
In this fame volume, I found two obfervations, 
which would be decilive, if time and othei circum- 
flances had permitted them to be made with luffici- 
ent accuracy. I have very carefully calculated them 
both. Mr. Mafkeline obferved at the illand of St. 
Helena, fituated at 1 5*55' South latitude, and ac- 
cording to Dr. Halley at 33' 17" of time Wed of 
the Obfervatory at Paris ; but this determination of the 
longitude does not feem fufficiently exadl. I have 
compared many obfervations of Jupiter’s Satellites 
immerlions and emerlions made at the illand of St. 
Helena by Mr. Mafkeline with the correfponding 
ones made at Paris at the Marine Obfervatory by Mr. 
Meffier, and have only found 3 1' 56" for the differ- 
ence of longitude between the two places ; and as 
the Marine Obfervatory is 2" Ead of the Royal Ob- 
fervatory, I think I may conclude that the place where 
Mr. Mafkeline obferved is only at 31' 54 ^ Wed of 
the Royal Obfervatory. 
Vol. LIV. X The 
