The Jewish year differed much in point of time, before, and after their sojourning in Egypt; and unless we could (which now is impossible) ascertain with more clearness whether their calculations were made by what is called the solar year, or the lunar year, that is, by the revolution of sun, or moonit is not possible to determine with accuracy the point. But all difficulties vanish in respect to the different periods of calculation, by whatever mode they are calculated, if we only are careful to consider the different dates from whence they take their calculation. As for examplein the promise the Lord made to Abram, (Genesis 15:13) concerning the affliction of his seed in a strange land, and their deliverance from it, the Lord marked the period, four hundred years; but in counting up the time when that deliverance took place, Moses makes it "four hundred and thirty years." But the period of both, is precisely the same, when the difference is allowed from the different dates of the commencement, or time, the account began. When it is said, as in Genesis 15:13 "four hundred years," it is connected with the birth of Isaac, which was thirty years after Abraham left Chaldea, and consequently, this period must be added to the account; and thus it will be found, by a parity of calculation in the several statements the Jewish year at different times give. See Hour.