To an observer on the Earth at _b_, the eastern limb of the Moon at _d_
seems to touch the western limb of the Sun at _W_, when the Moon is at
_M_; and the Sun’s Eclipse begins at _b_; appearing as at _A_ in Fig.
III at the left hand; but at the same moment of absolute time to an
observer at _a_ in Fig. II the western edge of the Moon at _c_ leaves
the eastern edge of the Sun at _V_, and the Eclipse ends, as at the
right hand _C_ of Fig. III. At the very same instant, to all those who
live on the Circle marked _1_ on the Earth _E_ in Fig. II, the Moon _M_
cuts off or darkens a twelfth part of the Sun _S_, and eclipses him one
Digit, as at _1_ in Fig. III: to those who live on the Circle marked _2_
in Fig. II the Moon cuts off two twelfth parts of the Sun, as at _2_ in
Fig. III: to those on the Circle _3_, three parts; and so on to the
center at _12_ in Fig. II, where the Sun is centrally eclipsed as at _B_
in the middle of Fig. III: under which Figure there is a scale of hours
and minutes, to shew at a mean state how long it is from the beginning
to the end of a central Eclipse of the Sun on the parallel of _London_;
and how many Digits are eclipsed at any particular time from the
beginning at _A_ to the middle at _B_, or the end at _C_. Thus in 16
minutes from the beginning, the Sun is two Digits eclipsed; in an hour
and five minutes, 8 Digits; and in an hour and thirty-seven minutes, 12
Digits.
[Sidenote: Fig. II.
The Velocity of the Moon’s shadow on the Earth.