39th appearance, on August 10, 1980, the Moon's shadow will have
passed the equator, and as the eclipse will take place nearly at
midnight (Greenwich M.T.), the phenomenon will be invisible in Europe,
Africa, and Asia. At every succeeding period the central line of the
eclipse will lie more and more to the S., until finally, on September
30, 2665, which will be its 78th appearance, it will vanish at the South
Pole.[8]

The operation of the Saros effects which have been specified above, may
be noticed in some of the groups of eclipses which have been much in
evidence (as will appear from a subsequent chapter), during the second
half of the 19th century. The following are two noteworthy Saros groups
of Solar eclipses:--

1842 July 8. | 1850 Aug. 7.
1860 " 18. | 1868 " 17.
1878 " 29. | 1886 " 29.
1896 Aug. 9. | 1904 Sept. 9.

If the curious reader will trace, by means of the _Nautical Almanac_
(or some other Almanac which deals with eclipses in adequate detail),
the geographical distribution of the foregoing eclipses on the Earth's
surface, he will see that they fulfil the statement made on p. 24
(_ante_), that a Saros eclipse when it reappears, does so in regions of
the Earth averaging 120 deg. of longitude to the W. of those in which it
had, on the last preceding occasion, been seen; and also that it
gradually works northwards or southwards.

But a given Saros eclipse in its successive reappearances undergoes
other transformations besides that of Terrestrial longitude. These are
well set forth by Professor Newcomb[9]:--

"Since every successive recurrence of such an eclipse throws the
conjunction 28' further toward the W. of the node, the conjunction must,
in process of time, take place so far back from the node that no eclipse
will occur, and the series will end. For the same reason there must be a
commencement to the series, the first eclipse being E. of the node. A
new eclipse thus entering will at first be a very small one, but will be
larger at every recurrence in each Saros. If it is an eclipse of the
Moon, it will be total from its 13th until its 36th recurrence. There
will be then about 13 partial eclipses, each of which will be smaller
than the last, when they will fail entirely, the conjunction taking
place so far from the node that the Moon does not touch the Earth's
shadow. The whole interval of time over which a series of lunar eclipses