BİRİNCİ FEN · ÜÇÜNCÜ BÂB · YEDİNCİ FASIL · Dördüncü Madde
**Article Four**
Concerning the measurement of lands and seas, travel upon them, and the divisions of distances.
Know, esteemed one, that astronomers and geometers are in agreement on this matter: Every entity within this sphere (the Earth) is a single globe; that is to say, a round ball, divided by longitude and latitude as follows. A circular belt has been posited running through its middle, dividing it into three hundred sixty segments.
According to the measurement of geometers, assuming the earth to be flat, without mountains or valleys, one degree of the Earth’s surface is found to be slightly more than twenty-two *fersahs*.
(*A fersah is an old unit of measure: One fersah equals three miles; each mile equals three thousand ziras; each zira thirty-two fingers; and each finger six grains of barley.*) With this reckoning, the degree of the Earth’s surface has been known to be sixty-six and two-thirds miles.
According to a *zira* calculation, one *fersah* of land is found to be nine thousand *ziras*.
One degree of the Earth's surface is traversed by walking in three stages. And it has been determined that one stage covers seven and a half *fersahs*. It has been experimentally established that one *fersah* can be covered in an hour with an average walking pace. Thus, the distance that can be covered in a day is seen to be twenty-two and a half miles. One degree of the Earth’s surface equals ten thousand steps; and each step consists of four feet. Each foot's length is calculated as sixteen fingers.
With ships traveling along the oceans’ edges, bays, and small seas between landmasses at an average pace, more than sixty nautical miles can be covered in a day. According to sailors, this distance is considered one degree of the Earth’s surface, termed a “channel.” However, when considering the movement of caravans and military marches, one degree of the Earth's surface is divided into three stages. For example, it has been accepted as reaching the village of Nardiban from the fertile Erzurum in a single day. If walking or movement is faster than this, they call it “middle pace” (seyr-i mutavassit), and one degree of the Earth’s surface is found to be two stages with middle pace. For example, it has been likened to a rider reaching Aşkale from Erzurum in a single day. If movement or walking is even faster than this, that degree is counted as one stage. For example, it is estimated to reach Karakulak from our city of Erzurum in a single day.
Thus, it is known that in the first style of walking, one-third of a degree is covered in a day; in the second, half a degree; and in the third, a full degree.
In essence, the distance of one degree on the round globe is, according to the aforementioned calculation, exactly ten thousand steps—no more. Nor is it more than two hundred thousand *ziras*, for one *zira* equals two feet, which is half a step. According to those learned in the sciences that reason by this principle, the time required to walk and traverse the globe – composed of earth and water and round like a ball – without accounting for mountains and seas, on a straight line has become apparent.
For example, if someone were to consider our beautiful city, the venerable Erzurum, as a mark, a beginning, and wished to circumnavigate the Earth; moving westward, passing through Tokat, Anatolia, Istanbul, Rumelia, and Frankish lands, he would reach the New World, continuing his journey in accordance with the sun’s course. From there, he could reach China and Maçin, then pass through India, Sind, and Turkistan to arrive at Samarkand. From there, passing through Bukhara and Turan, crossing the southern shore of Lake Shivan, traversing the provinces of Gence and Revan, he would return to our city of Erzurum.
Thus, he would have accomplished his desire, and this person would have come from the west and arrived from the east in relation to us. Similarly, someone wishing to circumnavigate the globe along lines of latitude would depart from our city of Erzurum, heading north, following the eastern shores of the Black Sea, reaching Faş, Abaza, and Azak. Passing through Moscow, he would reach the newly discovered land of Növözemle. As the sun is in the northern constellations, he would pass beneath the North Pole. Relative to us (our city of Erzurum), walking underground from pole to pole as the sun reaches the southern constellations, he would reach the South Pole. From there, following the ocean route, he would reach the land of Abyssinia, then Yemen, passing through Mecca and Medina, traversing the desert, and arrive at our clean city of Erzurum. Thus, he would also accomplish this desire (following the aforementioned route) and this person would have gone north and arrived from the south.
(As described above), someone wishing to circumnavigate the globe along lines of longitude or latitude, taking an average pace, would total one thousand eight hundred (1080) lodgings in a complete circuit. With a swift journey like riding, it is said that the total number of lodgings would be seven hundred twenty for walking. If he travels with a very rapid pace—like a messenger carrying urgent news—on a straight line, it is possible to circumnavigate the globe in three hundred sixty days. The truth lies only with Allah Almighty.