The circles E F, and G H, are called the Tropics, beyond which the sun never moves.
The line G F, which upon the globe is a circle, is termed the Ecliptic, in which the sun is perpetually moving from G to F, and F to G again. When the sun is in O, he is then in the Equinoctial, and the days and nights are of equal length to all the world, except under the Poles. When he is at F, which is called the Tropic of Cancer, days are at the longest to all those who dwell under the North side of the Equator. When the sun is at G, which is called the Tropic of Capricorn, days are at the longest to all those dwelling on the South side of the Equator, and at the shortest to those on the North side.
The circles LM and I K are called the Polar Circles, because to those inhabitants who dwell under these circles, the longest day is 24 hours; so that the sun sets not, but moves quite round their horizon. Thus much may suffice for the circles of the sphere; only note this, that every circle, whether great or small, is divided into 360 equal parts or degrees; so that a degree is no certain measure, but only the three hundred and sixtieth part of the circle; and these degrees are again supposed to be divided into sixty equal parts, which are called minutes. Now, therefore, if a circle which will reach round the earth be divided into 360 parts, then one of those parts is equal to a degree, which was looked upon by the ancients to be equal to sixty miles, and thus one mile was exactly equal to a minute.
Of the ZONES.
The Zones are certain tracts of land, whose boundaries are made by the circles before described, and are five in number, namely, the Torrid Zone; the Northern Temperate Zone; the Southern Temperate Zone; the Northern Frigid Zone; the Southern Frigid Zone. 1.The Torrid Zone contains all that space of land which lies between the circles E F and G H; for to those inhabitants who dwell betwixt the said limits, the sun, at some time of the year, becomes vertical, i.e. right over their heads. 2. The Northern Temperate Zone is all that space betwixt the circle E F, named the Tropic of Cancer, and the line L M, called the Northern Polar Circle; and to all the inhabitants within this compass, the sun, when in their several meridians, casteth their shadows directly north. 3. The Southern Temperate Zone is that tract of land which lies between the circular line G H, called the Tropic of Capricorn, and the Southern Polar Circle I K. To all the inhabitants within this space, the sun, when in their meridian, casteth their shadows full south. 4. The Northern Frigid Zone, is that part of the earth which lies between the Northern Polar Circle L M, and the North Pole at A; to all these inhabitants the sun, at a certain season, and when in the Tropic of Cancer, does not set, but moves in view quite round the horizon, casting their shadows every way. 5. The Southern Frigid Zone is that part of the earth which lies between the Southern Polar Circle I K, and the South Pole at B. To all the inhabitants within these limits, the sun, when in the Tropic of Capricorn, sets not, but moves in sight as before, casting their shadows also every way.
Of the CLIMATES.
The Climates are reckoned from the Equator to the Poles; under the Equator the day is always 12 hours long, and under the Polar Circles the longest day is 24 hours. Geographers make 24 climates between the Equator and each of the Polar Circles, because there are 24 half hours difference between the length of day under the Equator, and the longest day under the Polar Circle; so that any place where the longest day in that place is half an hour longer or shorter than that of another place, is of a different climate. The first climate begins at the Equator; the second where the longest day is 12 hours and a half; the third where it is 13 hours, and so on. There are in all 48 climates of hours, that is, four
[sic]
from the Equator to the Polar Circle, either Northward or Southward. Besides the aforesaid 48 climates of hours, there are 12 more, called climates of months, that is, six from each of the Polar Circles to the Poles. They are called climates of months, because the longest day in the end of the first climate is one whole month, the longest day at the end of the second two whole months, and so on.