"SAROS," and was used by the ancients (and can still be used by the
moderns in the way of a pastime) for the prediction of eclipses alike of
the Sun and of the Moon.

* * * * *

At the end of a Saros period, starting from any date that may have been
chosen, the Moon will be in the same position with respect to the Sun,
nearly in the same part of the heavens, nearly in the same part of its
orbit, and very nearly indeed at the same distance from its Node as at
the date chosen for the _terminus a quo_ of the Saros. But there are
trifling discrepancies in the case (the difference of about 11 hours
between 223 lunations and 19 returns of the Sun to the Moon's Node is
one) and these have an appreciable effect in disturbing not so much the
sequence of the eclipses in the next following Saros as their magnitude
and visibility at given places on the Earth's surface. Hence, a more
accurate succession will be obtained by combining 3 Saros periods,
making 54 years, 31 days; while, best of all, to secure an almost
perfect repetition of a series of eclipses will be a combination of 48
Saroses, making 865 years for the Moon; and of about 70 Saroses, or more
than 1200 years for the Sun.

These considerations are leading us rather too far afield. Let us return
to a more simple condition of things. The practical use of the Saros in
its most elementary conception is somewhat on this wise. Given 18 or 19
old Almanacs ranging, say, from 1880 to 1898, how can we turn to account
the information they afford us in order to obtain from them information
respecting the eclipses which will happen between 1899 and 1917?
Nothing easier. Add 18^y 10^d 7^h 42^m to the middle time of every
eclipse which took place between 1880 and 1898 beginning, say, with the
last of 1879 or the first of 1880, and we shall find what eclipses will
happen in 1898 and 17 following years, as witness by way of example the
following table:--

Error of Saros by
d. h. m. Exact Calculation.
MOON. 1879 Dec. 28 4 26 p.m.
(Mag. 0.17) 18 10 7 42
---------------------------------------------
(Mag. 0.16) 1898 Jan. 8 12 8 a.m. (civil time) +3 m.

d. h. m.
SUN. 1880 Jan. 11 10 48 p.m.
(Total) 18 10 7 42
---------------------------------------------
(Tot