near A the Moon should be at E, and in Conjunction with the Earth
the Moon will escape eclipse; if the Conjunction takes place with both
the Earth's shadow and the Moon a little further forward, say at F, the
Moon will be partially obscured; but if the Moon is at or very near its
node, as at G, it will be wholly involved in the Earth's shadow and a
total eclipse will be the result. In the case contemplated at G in the
diagram, the Moon is concentrically placed with respect to the shadow,
but the eclipse will equally be total even though the two bodies are not
concentrically disposed, so long as the Moon is wholly within the cone
of the Earth's shadow.[114]

Just as in the case of the Sun so with the Moon there are certain limits
on the ecliptic within which eclipses of the Moon _may_ take place,
other (narrower) limits within which they _must_ take place, and again
other limits beyond which they _cannot_ take place. Reverting to what
has been said on a previous page[115] with respect to these matters when
an eclipse of the Sun is in question it is only necessary to substitute
for the word "Conjunction," the word "Opposition"; and for 181/2 deg. and 151/4 deg.
of longitude the figures 121/2 deg. and 91/4 deg.. The limits in latitude will be
1 deg. 3' and 0 deg. 52' instead of 1 deg. 34' and 1 deg. 23'. These substitutions
made, the general ideas and facts stated with regard to the conditions
of an eclipse of the Sun will apply also to the one of the Moon.

It is to be noted that whereas eclipses of the Sun always begin on the
W. side of the Sun, eclipses of the Moon begin on the E. side of the
Moon. This difference arises from the fact that the Sun's movement in
the ecliptic is only apparent (it being the Earth which really moves),
whilst the Moon's movement is real.

Eclipses of the Moon, though more often and more widely visible than
eclipses of the Sun, do not offer by any means the same variety of
interesting or striking phenomena to the mere star-gazer, and it was
long thought that they were in a certain sense of no use to science.
Now, however, astronomers are inclined to utilise them for determining
the diameter of the Moon by noting occultations[116] of stars by the
Moon, the duration of a star's invisibility behind an eclipsed Moon
being a measure of the lunar diameter when such an observation is
properly transformed and "reduced." Observations of the heat radiated
(or rather reflected) by an eclipsed Moon have