2,709,700 5,074,490 7,000,000 10,665,830 36,444,220 66,780,420
195. These last numbers shew, that although we have the relative
distances of the Planets from the Sun to the greatest nicety, yet the
best observers have not hitherto been able to ascertain their true
distances to within less than a twelfth part of what they really are.
And therefore, we must wait with patience till the 6th of _June_, A. D.
1761; wishing that the Sky may then be clear to all places where there
are good Astronomers and accurate instruments for observing the Transit
of Venus over the Sun’s Disc at that time: as it will not happen again,
so as to be visible in Europe, in less than 235 years after.
[Sidenote: Why the celestial Poles seem to keep still in the same points
of the Heavens, notwithstanding the Earth’s motion round the
Sun.]
196. The Earth’s Axis produced to the Stars, being carried [50]parallel
to itself during the Earth’s annual revolution, describes a circle in
the Sphere of the fixed Stars equal to the Orbit of the Earth. But this
Orbit, though very large in itself, if viewed from the Stars, would
appear no bigger than a point; and consequently, the circle described in
the Sphere of the Stars by the Axis of the Earth produced, if viewed
from the Earth, must appear but as a point; that is, it’s diameter
appears too little to be measured by observation: for Dr. BRADLEY has
assured us, that if it had amounted to a single second, or two at most,
he should have perceived it in the great number of observations he has
made, especially upon γ _Dragonis_; and that it seemed to him very
probable that the annual Parallax of this Star is not so great as a
single second: and consequently, that it is above 400 thousand times
farther from us than the Sun. Hence the celestial poles seem to continue
in the same points of the Heavens throughout the year; which by no means
disproves the Earth’s annual motion, but plainly proves the distance of
the Stars to be exceeding great.
[Sidenote: The amazing velocity of light.