[ 4i ] 
tance at which it is certain fomc of them are placed, 
it' may require the Obfervations of many Ages, to 
determine the Laws of the apparent Changes, even 
of a Tingle Star : much more difficult therefore mutt 
it be, to fettle the Laws relating to all the mod re- 
markable Stars. 
When the Caufes, which affect the Places of all 
the Stars in general are known ? luch as the Precef 
Ton, Aberration, and Nutation 5 it may be of fingu- 
lar Ufe, to examine nicely the relative Situations of 
particular Stars : and efpecially of thofe of the greateft 
Luflrc, which, it may be prefumed lie neareft to 
us, and may therefore be fubject to more fenfible 
Changes ? either from their own Motion, or from 
that of our Syftem. And if at the fame time that 
the brighter Stars are compared with each other, we 
like wife determine the relative Portions of fome of 
the fmalleft that appear near them, whole Places can 
be afeertained with fufficient Exactnefs ? we may 
perhaps be able to judge to what Caufe the Change, 
if any be obfervable, is owing. The Uncertainty 
that we are at prelent under, with rcfpect to the 
Degree of Accuracy wherewith former Aftronomcrs 
could obferve, makes us unable to determine feveral 
Things, relating to the Subject that I am now fpeak- 
ing of : but the Improvements, which have of late 
Years been made in the Methods of taking the 
Places of the heavenly Bodies, are fo great, that a 
few Years may hereafter be fufficient, to fettle fomc 
Points? which cannot now be fettled, by comparing 
even the earlieft Obfervations with thofe of the pre- 
sent Age. 
F 
It 
