210. _Solar Ecliptic Limits._--The distances from the moon's node within which a new moon would throw some portion of its shadow on the earth so as to produce an eclipse of the sun are called the _solar ecliptic limits_. As in the case of the moon, there are _major_ and _minor_ ecliptic limits; the former being the limits within which an eclipse of the sun is _possible_ under some circumstances, and the latter those under which an eclipse is _inevitable_ under all circumstances. The limits within which a solar eclipse may occur are greater than those within which a lunar eclipse may occur. This will be evident from an examination of Fig. 235. Were the moon in that figure just outside of the lines _AB_ and _CD_, it will be seen that the penumbra of her shadow would just graze the earth: hence the moon must be somewhere within the space bounded by these lines in order to cause an eclipse of the sun. Now, these lines mark the prolongation to the sun of the cone of the umbra of the earth's shadow: hence, in order to produce an eclipse of the sun, new moon must occur somewhere within this prolongation of the umbra of the earth's shadow. Now, it is evident that the diameter of this cone is greater on the side of the earth toward the sun than on the opposite side: hence the solar ecliptic limits are greater than the lunar ecliptic limits. 211. _Solar Eclipses._--An observer in the umbra of the moon's shadow would see a _total_ eclipse of the sun, while one in the penumbra would see only a _partial_ eclipse. The magnitude of this partial eclipse would depend upon the distance of the observer from the umbra of the moon's shadow. [Illustration: Fig. 239.] [Illustration: Fig. 240.] The umbra of the moon's shadow is just about long enough to reach the earth. Sometimes the point of this shadow falls short of the earth's surface, as shown in Fig. 239, and sometimes it falls upon the earth, as shown in Fig. 240, according to the varying distance of the sun and moon from the earth. The diameter of the umbra at the surface of the earth is seldom more than a hundred miles: hence the belt of a total eclipse is, on the average, not more than a hundred miles wide; and a total eclipse seldom lasts more than five or six minutes, and sometimes only a few seconds. Owing, however, to the rotation of the earth, the umbra of the moon's shadow may pass over a long reach of the earth's surface. Fig. 241 shows the track of the umbra of the moon's shadow over the earth in the total eclipse of 1860. [Illustration: Fig. 241.] [Illustration: Fig. 242.] Fig. 242 shows the track of the total eclipse of 1871 across India and the adjacent seas. [Illustration: Fig. 243.] [Illustration: Fig. 244.]