Part 2c

The Seven Zones Icon

January 28, 2020

The ancient philosophers divided the cultivated part of the earth in the north into seven zones by means of imaginary lines running from west to east. They maintain that these zones have different latitudinal extensions. This will be discussed in detail.

The first zone runs along the equator, north of it. South of it, there is only the civilization to which reference was made by Ptolemy. Beyond that are waste regions and sandy deserts, up to the circle of water which is called the Surrounding Sea.

To the north, the first zone is followed, successively, by the second through the seventh zones. (The seventh zone) constitutes the northern limit of civilization. Beyond it are only empty and waste regions, down to the Surrounding Sea as (in the south). However, the empty regions in the south are much larger than those in the north.*

As to latitudes and length of days in the various zones, it should be known that the two poles of the firmament are upon the horizon at the equator in the west and the east.

It should be known that, as was mentioned above, the philosophers divided the cultivated part of the earth into seven parts from south to north. These parts they called zones. The whole of the cultivated area is distributed over these zones. Each zone extends from west to east.

The first zone runs from west to east with the equator as its southern border.Beyond it, there are only waste regions and sandy deserts, and civilization of a sort that, if it actually exists, is more like non-civilization. To the north, the first zone is followed, successively, by the second through the seventh zones.

The seventh zone constitutes the northern limit of civilization. Beyond it (to the north) are only empty and waste regions until the Surrounding Sea is reached. The situation is the same here as it is beyond the first zone to the south. However, the empty areas in the north are much smaller than those in the south. The sun there is at the zenith. As we follow the cultivated part of the earth farther and farther north, the north pole ascends slightly, and the south pole descends correspondingly, (at the horizon). Furthermore, the sun moves a corresponding distance from (its zenith at) the equinoctial line. These three distances are equal to each other. Each of them is called geographical latitude. This is well known to the scholars who determine the (prayer) times. People hold different opinions as to the latitudinal extension (of the cultivated part of the earth) and as to the latitudinal extension (breadth) of the various zones. Ptolemy holds the opinion that the latitudinal extension of the entire cultivated part of the earth is 771/ 2 . The latitudinal extension of the cultivated part beyond the equator to the south is 11° .48a Thus, the latitudinal extension of the zones in the north is 66 1 / . According to 2 him, the first zone extends to 16° ; 48b the second to 20° ; the third to 27° ; the fourth to 33° ; the fifth to 38° ; the sixth to 43° ; the seventh to 48° .49 He then determined the degree on the firmament as having a length of 662/ miles, (were it to be) measured on the surface 3 earth. 50 of the

  • Zone 1 from south to north is 1,067 miles wide
  • Zone 2 is 2,333 miles
  • Zone 3 is 2,790 miles
  • Zone 4 is 2,185 miles
  • Zone 5 is 2,520 miles
  • Zone 6 is 2,840 miles
  • Zone 7 is 3,150 miles

The length of night and day differs in the various zones by reason of the declination of the sun from the equinoctial line and the elevation of the north pole above the horizon. This causes a difference in the arcs of day and night.

At the boundary of the first zone, the longest night-which occurs when the sun enters Capricorn-and the longest day which occurs when the sun enters Cancer-reach a maximum of thirteen hours. The same is the case at the boundary of the second zone in the north.

The length of day there reaches its maximum of thirteen and one-half hours when the sun enters Cancer, the summer tropic. The longest night -when the sun enters Capricorn, the winter tropic is as long. For the shortest day and night, there thus remains the difference between thirteen and one-half and twenty-four, which is the combined number of hours of day and night, or one complete revolution of the firmament. The same is the case also at the boundary of the third zone in the north, where night and day reach a maximum length of fourteen hours; at the boundary of the fourth zone, where they reach a maximum length of fourteen and one-half hours; at the boundary of the fifth zone, where they reach a maximum length of 15 hours; at the boundary of the sixth zone, where they reach a maximum length of fifteen and one-half hours; and at the boundary of the seventh zone, where they reach a maximum length of sixteen hours.

There, civilization ends.

The difference in the maximum length of night and day in the various zones, consequently, is an evenly distributed, gradual increase of half an hour in each, all the way from the first zone in the south to the last zone in the north.

In connection with these zones, “geographical latitude” refers to the distance between the sun at its zenith in a given place and the equinoctial line where it is at thezenith on the equator. It likewise corresponds to the depression of the south pole below the horizon in that particular place, as well as to the elevation of the north pole.

As was mentioned before, 51 these three distances are equal to each other. They are called “geographical latitude.”

At the boundary of the first zone, the longest night which occurs when the sun enters Capricorn - and the longest day-which occurs when the sun enters Cancer-reach, according to Ptolemy, a maximum of twelve and one-half hours; at the boundary of the second zone, a maximum of 13 hours; at the boundary of the third zone, a maximum of 13.5 hours; at the boundary of the fourth zone, a maximum of fourteen hours; at the boundary of the fifth zone, a maximum of one half-hour more; at the boundary of the sixth zone, a maximum of fifteen hours; and at the boundary of the seventh zone, a maximum of one half-hour more. For the shortest day and night, there thus remains the difference between the last figure and twenty-four, which is the combined number of hours of day and night, or one complete revolution of the firmament.

The difference in the maximum length of night and day in the various zones, consequently, is an evenly distributed, gradual increase of half an hour in each, all the way from the first zone in the south to the last zone in the north.* Ishaq b. al-Hasan al-Khazini maintains that the latitudinal extension of civilization beyond the equator (to the south) is 16 ° 25’, and the longest night and day there, thirteen hours. The latitudinal extension of the first zone and the length of day and night there are the same as beyond the equator (to the south). The second zone extends to 24°, 51a and the length of its (longest) day and night at its farthest point is thirteen and one-half hours. For the third zone, the figures are 30 ° and fourteen hours. For the fourth zone, they are 36 ° and fourteen and one-half hours. For the fifth zone, they are 41 ° and fifteen hours. For the sixth zone, they are 45 ° and fifteen and one-half hours. For the seventh zone, they are 48 1 / 2 ° and sixteen hours. The latitudinal extension of civilization beyond the seventh zone (to the north) reaches from the boundary of the seventh zone to (latitude) 63 ° , and the length of the (longest) day and night to twenty hours.

Other leading scholars in the discipline, apart from Ishaq al-Khazini, maintain that the latitudinal extension of the cultivated area beyond the equator (to the south) is 16 ° 27'.

The first zone extends to 20 ° 15’; the second to 27 ° 13’; the third to 33 ° 20’; the fourth to 38 1 / 2 ° ; 52 the fifth to 43 ° ; the sixth to 47 ° 53’; or, according to another opinion, to 46 ° 50’; and the seventh to 51 ° 53’. Civilization beyond the seventh zone extends to 77 ° . In Abu Jafar al-Khazini,53 one of the leading scholars in the discipline, one also finds that the latitudinal extension of the first zone is from 1 ° to 20 ° 13’; of the second, to 27 ° 13’; of the third, to 33° 39’; of the fourth, to 38° 23’; of the fifth, to 42 ° 58’; of the sixth, to 47 ° 2’; and of the seventh, to 60°45’. 5 4 This is as much as I know about the different opinions concerning latitudinal extension and length of day and night in the zones and concerning their width as indicated in miles.

The geographers have subdivided each of the seven zones lengthwise from west to east in ten equal sections.

They mention the countries, cities, mountains, and rivers of each section, and the traveling distances between them. We shall now briefly summarize the best-known countries, rivers, and seas of each section.

Our model will be the data set forth in the Nuzhat al-mushtaq which al-‘Alawi al-Idrisi al-Hammudi composed for the Christian king of Sicily, Roger, the son of Roger.

Al-Idrisi’s family had given up its rule of Malaga, and he had settled at (Roger’s) court in Sicily. He composed the book in the middle of the sixth [twelfth] century. He utilized many books by authors such as al-Mas’udi, Ibn Khurradadhbih, al-Hawgali, al-‘Udhri, Ishaq al-Munajjim, 57 Ptolemy and others.

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