CHAP. I.
Of the Day.
THe Day is either Astronomical or Political, otherwise called Civil; The Astronomical is that which is so termed by Astrono∣mers, [ 10] and is divided into Natural, and Arti∣ficial.
1, The Natural Day is that interval of Time wherein the Sun departing from any Point of the Heavens, or from the Meridian returns again to the same Point; or otherwise it may be defined, The Suns conversion from any first Meridian to the same again, which is performed in the space of 24 equal Hours.
2, The Artificial Day is the space of Time [ 20] from Sun-rising to Sun-setting; or the whole Time of the Suns-shining in our Hemisphere, the oppo∣site Time whereof must accordingly be called Artificial Night.
Note, That the Artificial Day differs from the Natural, in regard the Natural is always and every where the same, wheras the Artificial hath almost always a perpetual Mutation, especially in Regions remote from the Aequator; for, as I said, the Artificial Day comprehends only the [ 30] space of Time comprehended between the Suns rising and Setting, being shorter in Winter and longer in Summer.
Note Secondly, That the Days are longer in Summer by reason of the Suns longer continuing above the Horizon, and the larger Arches of Heaven the Sun runs through in respect to our Horizon, as you may see in the Description of the Sphaere: On the contrary, the Diurnal Arches the Sun makes in Winter, are shorter. The Di∣urnal, and Nocturnal Arches appear almost all-equal. [ 40] Not to speak of the Twilights, being an impression of Light from the Sun-beams upon the Air, either before Sun-rising, which is called Di∣luculum, or Day-break, or in the Evening after Sun-set.
Note Thirdly, That the Natural Day hath not the same beginning among all People, but is de∣termined according to the different institution of each of them. The Babilonians use to denominate [ 50] the Day from one Sun-rising to another. The Itali∣ans on the contrary from one Sun-setting to ano∣ther, and accordingly they number their Hours. The Antient Romans, and accordingly the Romish Church at this day reckon from Midnight to Mid∣night. The Arabians and Astronomers from Moon to Moon, because the Sun and Stars keep always the same regularity to each other, in respect of the Meridian Circle, but not in respect of the Horizon, which always varies according to the variety of the Polar Elevation.
Nor can we in respect to the Holy Scriptures omit the Custom of the antient Jewes, who as they were commanded by God, began all their Feasts from the foregoing Sun-setting, according to that of Leviticus, from Evening to Evening ye shall celebrate your Sabbaths. Contrarily the Tyrians began their Day from the Sun-rising, and probably in this matter they differ'd not from the Babilonians, and other Neihbouring Provinces, who computed the Hours not from Sun-rising, but from its Setting.
Further Note, This Natural Day consisting of Artificial Day and Night, is called Civil, or Poli∣tical, as it takes beginning, or ending from the different Institution of People and Countries; And of these Political Days some Festival or Holy-Days, in which Shops are shut up, and common Works laid aside, or Working-Days allotted for the exercise of all manner of Works and Pro∣fessions; and these Days are noted in these Tables, or Books, which from the Arabians we call Al∣manacks, and from the Latins, Calenders; for a Calender is the Order and Series of all Months, Lunations, and Festival-Days, which happen through the Year; and it is called Calender from the Calends, which are the first Days of every Month.