Chap. 10.] ACCOUNT OF THE WOELD. 39 
while an eclipse of tlie moon takes place only when slie is 
at the full, and is always a little farther advanced than the 
preceding eclipsed Now there are eclipses of both these 
stars in every year, which take place below the earth, at 
stated days and hours ; and when they are above it^ they are 
not always visible, sometimes on account of the clouds, but 
more frequently, from the globe of the earth being opposed 
to the vault of the heavens^. It was discovered two hundred 
years ago, by the sagacity of Hipparchus, that the moon is 
sometimes eclipsed after an interval of five months, and the 
sun after an interval of seven ; also, that he becomes invi- 
sible, while above the horizon, twice in every thirty days, 
but that this is seen in difierent places at different times. 
But the most wonderful circumstance is, that while it is ad- 
mitted that the moon is darkened by the shadow of the earth, 
this occurs at one time on its western, and at another time 
on its eastern side. And farther, that although, after the 
rising of the sun, that darkening shadow ought to be below 
the earth, yet it has once happened, that the moon has been 
ecKpsed in the west, while both the luminaries have been above 
the horizon^. And as to their both being invisible in the 
space of fifteen days, this very thing happened w^hile the 
Vespasians were emperors, the father being consul for the 
third time, and the son for the second^. 
^ " Hoc enim periodo (223 mensium) plerumque redeimt eclipses, non 
multum differentes, denis tamen gradibus zodiaci antecedentes j" Kepler, 
as quoted by Alexandre, in Lemaire, ii. 238. 
2 The terms *' sub terra" and " supeme" are interpreted, by most of the 
commentators, below and above the horizon respectively ; see Marcus ui 
Ajasson, ii. 307. 
3 " globo terrse obstante convexitatibus mundi." The term convexus^ 
as apphed to the heavens, or visible firmament, simply signifies arched j 
not opposed to concave^ like the EngUsh word convex. 
^ This poiat is discussed by Ptolemy, Magn. Const, vi. 6 ; "De distantia 
eclipticorum mensium." See also the remarks of Hardouin iu Lemaire, 
ii. 260, 261 ; and of Poinsmet, i. 67. 
^ These are styled horizontal echpses ; they depend on the refractive 
power of the atmosphere, causiag the sun to be visible above the horizon, 
although it is actually below it. Brotier states, that ecHpses of this de- 
scription occurred on the l7th July, 1590, on the 30th November, 1648, 
and on the 16th January, 1660 ; Lemaire, ii. 260. 
^ This is supposed to have been in the year 72 of our sera, when it is 
said that the sun was ecHpsed, in Italy, on the 8th, and the moon on the 
22nd of February ; see Hardouia and Alexandre, in Lemaire, ii. 261* 
