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L Conflderations on the Change of the Latitudes 
of tome of the principal fixt Stars. ^By Edmund 
Halley, R. S. Sec. 
H Aving of late had occafion to examine the quan- 
tity of the Prcceflion of the Equinodial Points, 
I cook the pains to compare the Declinations of the fixe 
Stars delivered by Ptolomy, in the 3^;^ Chapter of the yth 
Book of his Almag, as obferved by Timocharis and Ari- 
fljUus near 300 Years before Chrift, and by Hipparchus 
about I/O Years after them, that is about 130 Years 
before Chriji, with what we now find : and by the re- 
fult of very many Calculations, I concluded that the 
fixt Stars in 1800 Years were advanced fomevvhat more 
than degrees in Longitude, or that the Preceflion is 
fomewhat more than j>er arm But that with To much 
uncertainty, by reafon of the imperfect Obfervations of 
the Ancients, that I have chofen in my Tables to adhere 
to the even proportion of five Minutes in fix Years, 
which from other Principles we are aflured is very near 
the Truth. But while I was upon this Enquiry, I was 
furprized to find the Latitudes of three of the principal 
Scars in Heaven directly to contradid the fuppoied great- 
er Obliquity of the Ediptick, which feenis confirmed by 
the Latitudes of moft of the reft; they being fet down 
in the old Catalogue, as if the Plain of the Earths Orb 
had chang’d its Situation, among the f«xt Stars, about 
20' fince the time of Hipparchus. Particularly all the 
Stars in are put down, thofe to the 
the Eclipttek, with fo much lefs Latitude rhan we fmd, 
and thofe to the Souihvrard With fo much more Southerly 
Lati- 
