that part of the natural day during which the sun is underneath the horizon; or that time when it is dark or dusky. Night was originally divided by the Hebrews and other eastern nations into three parts or watches. But the Romans, and after them the Jews, divided the night into four parts or watches; the first of which began at sunset, and lasted till nine at night, according to our way of reckoning; the second lasted till midnight; the third extended to three in the morning; and the fourth ended at sunrise. The ancient Gauls and Germans divided their time, not by days, but by nights; the Anglo-Saxons followed the same method of reckoning; and the people of Iceland and the Arabs do the same at this day. The length and shortness of the night or of darkness is according to the season of the year and position of the place; and the causes of this variation are now well known. See Astronomy.