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/ 
which fully convinced me, that I had guefied rightly 
as to the Caufc of th z'Thanomena. This Circum- 
ftance proves likewife, that if there be a gradual 
Diminution of the Obliquity of the Ecliptic 5 it 
does not arife only from an Alteration in the Po- 
rtion of the Earth’s Axis, but rather from fome 
Change in the Plane of the Ecliptic itfelf : becaufe 
the Stars, at the fkid of the Period of the Moon’s 
Nodes, appeared in the fame Places, with refped 
to the Equator, as they ought to have done, if the 
Earth’s Axis had retained the fame Inclination to an 
invariable Plane. 
During the Courfe of my Obfervations, our in- 
genious Secretary of the Royal Society , Mr. John 
Machin , being employed in confidering the Theory 
of Gravity; and its Confequences, with regard to 
the Celeftial Motions ; I acquainted him with the 
Rhanomena that I had obferved : and at the fame 
time mentioned, what I fufpeded to be the Caufe 
of them. He foon after fent me a Table, contain- 
ing the Quantity of the annual Precefiion in the 
various Pofitions of the Moon’s Nodes, as alfo the 
correfponding Nutations of the Earth’s Axis 5 which 
was computed upon the Suppofition, that the mean 
annual Precefiion is yo", and that the Whole is 
governed by the Pole of the Moon’s Orbit only : 
and therefore he imagined, that the Numbers in the 
Table would be too larger as in Fad they were 
found to be. But it appeared, that the Changes 
which I had obferved, both in the annual Preccf- 
fion and Nutation, kept the fame Law, as to in- 
creafing and decreafing, with the Numbers of his 
Table. Thofe were calculated upon the Suppofition, 
that 
