Why the planets appear larger in the East than they do overhead,
whereas the contrary should be the case, as they are 3500 miles
nearer to us when in mid sky than when on the horizon.

All the degrees of the elements, through which the images of the
celestial bodies pass to reach the eye, are equal curves and the
angles by which the central line of those images passes through
them, are unequal angles [Footnote 13: _inequali_, here and
elsewhere does not mean unequal in the sense of not being equal to
each other, but angles which are not right angles.]; and the
distance is greater, as is shown by the excess of _a b_ beyond _a
d_; and the enlargement of these celestial bodies on the horizon is
shown by the 9th of the 7th.

Observations on the stars.