d black shield." We thus have examples of the two distinct
appearances alluded to in Chapter VII., _i.e._ when the moon appears of
a coppery-red colour, and when it is entirely darkened.

It appears, indeed, that, in the majority of lunar eclipses on record,
the moon has appeared of a ruddy, or rather of a coppery hue, and the
details on its surface have been thus rendered visible. One of the best
examples of a _bright_ eclipse of this kind is that of the 19th March
1848, when the illumination of our satellite was so great that many
persons could not believe that an eclipse was actually taking place. A
certain Mr. Foster, who observed this eclipse from Bruges, states that
the markings on the lunar disc were almost as visible as on an "ordinary
dull moonlight night." He goes on to say that the British Consul at
Ghent, not knowing that there had been any eclipse, wrote to him for an
explanation of the red colour of the moon on that evening.

Out of the _dark_ eclipses recorded, perhaps the best example is that
of May 18, 1761, observed by Wargentin at Stockholm. On this occasion
the lunar disc is said to have disappeared so completely, that it could
not be discovered even with the telescope. Another such instance is the
eclipse of June 10, 1816, observed from London. The summer of that year
was particularly wet--a point worthy of notice in connection with the
theory that these different appearances are due to the varying state of
our earth's atmosphere.

Sometimes, indeed, it has happened that an eclipse of the moon has
partaken of both appearances, part of the disc being visible and part
invisible. An instance of this occurred in the eclipse of July 12, 1870,
when the late Rev. S.J. Johnson, one of the leading authorities on
eclipses, who observed it, states that he found one-half the moon's
surface quite invisible, both with the naked eye and with the telescope.

In addition to the examples given above, there are three total lunar
eclipses which deserve especial mention.

1. A.D. 755, November 23. During the progress of this eclipse the moon
occulted the star Aldebaran in the constellation of Taurus.

2. A.D. 1493, April 2. This is the celebrated eclipse which is said to
have so well served the purposes of Christopher Columbus. Certain
natives having refused to supply him with provisions when in sore
straits, he announced to them that the moon would be darkened as a sign
of the anger of heaven. When the event duly