7. Chap. 7.-Of The Eclipses Of The Moon And The Sun.

CHAP. 7.—OF THE ECLIPSES OF THE MOON AND THE SUN.

For it is evident that the sun is hid by the intervention[1] of the moon, and the moon by the opposition[2] of the earth, and that these changes are mutual, the moon, by her interposition[3], taking the rays of the sun from the earth, and the earth from the moon. As she advances darkness is suddenly produced, and again the sun is obscured by her shade; for night is nothing more than the shade of the earth. The figure of this shade is like that of a pyramid or an inverted top[4]; and the moon enters it only near its point, and it does not exceed the height of the moon, for there is no other star which is obscured in the same manner, while a figure of this kind always terminates in a point. The flight of birds, when very lofty, shows that shadows do not extend beyond a certain distance; their limit appears to be the termination of the air and the commencement of the æther. Above the moon everything is pure and full of an eternal light. The stars are visible to us in the night, in the same way that other luminous bodies are seen in the dark. It is from these causes that the moon is eclipsed during the night[5]. The two kinds of eclipses are not, however, at the stated monthly periods, on account of the obliquity of the zodiac, and the irregularly wandering course of the moon, as stated above; besides that the motions of these stars do not always occur exactly at the same points[6].

1. The terms here employed are respectively interventus, objectio, and interpositus; it may be doubted whether the author intended to employ them in the precise sense which is indicated by their etymology.

2. The terms here employed are respectively interventus, objectio, and interpositus; it may be doubted whether the author intended to employ them in the precise sense which is indicated by their etymology.

3. The terms here employed are respectively interventus, objectio, and interpositus; it may be doubted whether the author intended to employ them in the precise sense which is indicated by their etymology.

4. "metæ et turbini inverso." The metæ were small pyramids placed at the two extremities of the spina, or central division of the circus: see Montfaucon, v. iii. p. 176; Adam, p. 341.

5. The eclipses of the moon are only visible when the spectator is so situated as to be able to observe the shadow of the earth, or is on that side of the earth which is turned from the sun.

6. "non semper in scrupulis partium congruente siderum motu." On the term scrupulus Hardouin remarks, "Scrupuli, nodi sunt, in quibus circuli, quos in suo cursu Sol et Luna efficiunt, se mutuo secant." Lemaire, ii. 251. Ptolemy, Magn. Const. vi. 6–11, gives a full and generally correct account of the principal phenomena of eclipses.