Summer and Winter Solstices.
The Natural Day is divided into 24 Hours, each hour into 60 Minutes, each minute into 60 Seconds, &c. The Artificial Days are always unequal to all the inhabitants that are not under the equator, except when the Sun is in the equinoctial points ♈ and ♋, which happens (according to our way of reckoning) about the 21st of March, and the 23d of September; at those times the Sun rises at six and sets at six to all the inhabitants of the Earth. These days are called the Equinoxes, or Equinoctial Days; the first of which, or when the Sun is in the first point of Aries, is called the Vernal Equinox, and the latter is called the Autumnal Equinox. In all places where the Sun descends below the horizon, excepting under the equator, the days continually lengthen or shorten, and that faster or slower, according as the Sun is nearer to, or further from the equinoctial, until he arrives to either of the Solstitial Points ♋ or ♑. At those times the Sun seems to stand still for a few days, and then begins to return with a slow motion towards the equinoctial, still hastening his pace as he comes nearer to it: The Sun enters the tropics of ♋ and ♑, about the 21st of June, and the 22d of December, which days are sometimes called the Solstices; the first of which we call the Summer Solstice, and the latter the Winter Solstice.
The different beginning of the day.
All nations do not begin their day, and reckon their hours alike. In Great-Britain. France, and Spain, and in most places in Europe, the days is reckoned to begin at midnight, from whence is counted twelve hours ’till noon, then twelve hours more ’till next midnight, which makes a compleat day; yet the Astronomers (in these countries) commonly begin their day at noon, and so reckon 24 hours ’till next noon, and not twice twelve, according to the vulgar computation.
Babylonish Hours.
Italian Hours.
The Babylonians began their day at Sun-rising, and reckoned 24 hours ’till he rose again! This way of computation we call the Babylonish Hours. In several parts of Germany they count their hours from Sun-setting, calling the first hour after the Sun has set, the first hour, &c. ’till he sets the next day, which they call the 24th hour: These are commonly called the Italian Hours. According to both these ways of computation, their hours are commonly either a little greater or less than the ¹/₂₄ part of a natural day, in proportion as the Sun rises or sets sooner or later in the succeeding days. They have also this inconvenience, that their mid-day and midnight happen on different hours, according to the seasons of the year.
Jewish Hours.
Planetary Hours.
The Jews and the Romans formerly divided the artificial days and nights each into 12 equal parts; these are termed the Jewish Hours, and are of different lengths, according to the seasons of the year; a Jewish Hour in summer being longer than one in winter, and a night-hour shorter. This method of computation is now in use among the Turks, and the hours are stiled the first hour, second hour, &c. of the day or night; so that Mid-day always falls on the sixth hour of the day. These hours are also called Planetary Hours, because in every hour one of the seven Planets were suppose to preside over the World, and so take it by turns. The first hour after Sun-rising on Sunday was allotted to the Sun; the next to Venus, the third to Mercury; and the rest in order to the Moon, Saturn, Jupiter, and Mars. By this means on the first hour of the next day, the Moon presided, and so gave the name to that day; and so seven days by this method had names given them from the Planets that were supposed to govern on the first hour.