[ 9 3 
Obfcrvations themfelves ; which plainly prove, that 
at the End of the full Period of the Deviations which 
I am going to mention, the Stars are found to have 
the fame Pofitions by the Inftrumcnt, as they ought 
to have, fuppofmg the Line of Collimation to have 
continued unaltered from the Time when I firft began 
to obferve. 
I have already taken notice, in what manner this 
Phenomenon difeover'd itfelf to me at the End of 
my firft Year's Obfervations, viz. by a greater ap* 
parent Change of Declination in the Stars near the 
Equinoctial Colure, than could arife from a Pre- 
ceflion of 50" in a Year ; the mean Quantity now 
ufually allowed by Aftronomers. But there appear- 
ing at the fame time, an EfFeCt of a quite contrary 
Nature, in fome Stars near the Solftitial Colure, 
which feem'd to alter their Declination lefs than a 
Precellion of 50" required,* I was thereby con- 
vinced, that all the Phenomena , in the different 
Stars, could not be accounted for, merely by fup- 
pofing, that I had affumed a wrong Quantity for the 
Precellion of the Equinoctial Points. 
At firft, I had a Sufpicion, that fome of thefe fmall 
apparent Alterations in the Places of the Stars, might 
poffibly be occafioned by a Change, in the Materials, 
or in the Pofition of the Parts of my SeCtor : But, 
upon confidering how firmly the Arc, on which 
the Divifions or Points are made, is fattened to the 
Plate, wherein the Wire is fixed that lies in the 
Focus of the Object-Glafs; I faw no Reafon to ap- 
prehend, that any Change could have happened in 
the Pofition of that Wire and thofe Points. The 
Sufpenfion therefore of the Plummet being the mod 
likely Caufe, from whence 1 conceived any Uncer- 
B taint/ 
