C 895 ] 
mean, which, in general, is very fmall, and fcarce 
exceeds 2", except in two obfervations, in one of 
which it amounts to 3", and the other to 4 : but 
thefe differ as much from the mean of the fix otheL 
obfervations made at the fame feafon of the .yeai . 
Thus, affirming a parallax, the obfervations will be 
found to agree as well with that fuppofition, as they 
do with one another. But if the obfervations aie con- 
fidered in themfelves, without any allowance foi pa- 
rallax, they will differ fenfibly from one another : 
nor is this difference to be found only in two obier- 
vations, in which cafe, it may eafily be attributed to 
the account of the unavoidable errors; but fiv^ ob- 
fervations in July oppoled to two in Decembei and 
January, make the zenith diftances vary 8 in the 
direction, which a parallax ought to produce. 
I am aware, that it may be objected, that two obfei- 
vations made in the winter feaion in December and 
January, at one of the maxima of the paiallax, are 
too few to determine a point of fuch confequence, and 
readily agree, that the argument is weakened in pro- 
portion to the paucity of the obfervations : but then, 
ft fhould alfo be confidered, that the obfervations 
made in March and April concur with the reft in 
fupporting the fuppofition of a parallax ; and,. upon 
the whole, the obfervations will, perhaps, be judged 
to afford a fufficient prefumption of the exiftence of 
a parallax, to encourage the undertaking a careful 
trial. It is upon the ftrength of this prefumption, 
principally, that I have ventured to lay thefe thoughts 
before the Royal Society, whole members may juftly 
claim the honour of having made the greateft at- 
tempts towards demonftrating this important, but 
yet undetermined point in aftronomy. 
J liXA IX 0. rdr- 
