SEASONS

, certain portions or quarters of the year, distinguished by the signs which the sun then enters. Upon them depend the different temperatures of the air, different works in tillage, &c.

The year is divided into four Seasons, spring, summer, autumn, winter, which take their beginnings when the sun enters the first point of the signs Aries, Cancer, Libra, Capricorn.

The Seasons are very well illustrated by fig. 1, plate viii; where the candle at I represents the sun in the centre, about which the earth moves in the ecliptic ABCD, which cuts the equinoctial abcd in the two equinoxes E and G. When the earth is in these two points, it is evident that the sun equally illuminates both the poles, and makes the days and nights equal all over the earth. But while the earth moves from G by C to , the upper or north pole becomes more and more enlightened, the days become longer, and the nights shorter; so that when the earth is at , or the sun at , our days are at the longest, as at midsummer. While the earth moves from by D to E, our days continually decrease, by the north pole gradually declining from the sun, till at E or autumn they become equal to the nights, or 12 hours long. Again, while the earth moves from E by A to F, the north pole becomes always more and more involved in darkness, and the days grow always shorter, till at F or , when it is midwinter to the inhabitants of the northern hemisphere. Lastly, while the earth moves from by B to G, the north parts come more and more out of darkness, and the days grow continually longer, till at G the two poles are equally enlightened, and the days equal to the nights again. And so on continually year after year.