by the Moon.

It was calculated by Du Sejour that the greatest possible duration of
the total phase of a Solar eclipse at the equator would be 7^m 58^s, and
for the latitude of Paris 6^m 10^s. In the case of an annular eclipse
the figures would be 12^m 24^s for the equator, and 9^m 56^s for the
latitude of Paris. These figures contemplate a combination of all the
most favourable circumstances possible; as a matter of fact, I believe
that the greatest length of total phase which has been actually known
was 61/2^m and that was in the case of the eclipse of August 29, 1886. It
was in the open Atlantic that this duration occurred, but it was not
observed. The maximum observed obscuration during this eclipse was no
more than 4^m.

Though total eclipses of the Sun happen with tolerable frequency so far
as regards the Earth as a whole, yet they are exceedingly rare at any
given place. Take London, for instance. From the calculations of Hind,
confirmed by Maguire,[11] it may be considered as an established fact
that there was no total eclipse visible at London between A.D. 878 and
1715, an interval of 837 years. The next one visible at London, though
uncertain, is also a very long way off. There will be a total eclipse on
August 11, 1999, which will come as near to London as the Isle of Wight,
but Hind, writing in 1871, said that he doubted whether there would be
any other total eclipse "visible _in England_ for 250 years[12] from the
present time." Maguire states that the Sun has been eclipsed, besides
twice at London, also twice at Dublin, and no fewer than five times at
Edinburgh during the 846 years examined by him. In fact that every part
of the British Isles has seen a total eclipse at some time or other
between A.D. 878 and 1724 except a small tract of country at Dingle, on
the West coast of Ireland. The longest totality was on June 15, 885,
namely, 4^m 55^s, and the shortest in July 16, 1330, namely, 0^m 56^s.

Contrast with this the obscure island of Blanquilla, off the northern
coast of Venezuela. The inhabitants of that island not long ago had the
choice of two total eclipses within three and a half years, namely,
August 29, 1886, and December 22, 1889; whilst Yellowstone, U.S., had
two in twelve years (July 29, 1878, and January 1, 1889).

Counting from first to last, Du Sejour found that at the equator an
eclipse of the Sun might last 4^h 29^m, and at the latitude of Paris 3^h
26^m. These intervals, of course, c