Claudius Ptolemaeus; Giovanni Antonio Magini — Geographiae universae tum veteris, tum novae (1597)

true. The island of Thule lies above Scotland, the Hebrides, and the Orkney islands toward the North and East, and is called Shetland today, and Thylinsel by sailors. Then he reports that the same Marinus places the last parallel of the known Earth from the South under the winter tropic, which recedes nearly 24 degrees from the equator to the South, which parallel he draws through the region of Agisymba in Ethiopia and through the Prasum promontory. In this, indeed, Marinus is reproved and corrected by Ptolemy, who affirms below in the tenth chapter that this parallel is only 16 degrees and 25 minutes distant from the equator to the South. Whence the latitude of the known Earth is not 87 degrees, as Marinus thought, but only 80 degrees, as is evident from Ptolemy.

Regarding the location of the region of Agisymba, there is doubt among recent authors. For Mercator constitutes it on this side of the equator in the land of the Nigritae. But Sanutus, to whom more belief is to be given in this matter, places it beyond the equator in the kingdom of Benomotaxa or Monopotapa, and there exists today a building called Simbaca. The Prasum promontory, however, is thought today to be the head of Mozambique, which is situated in lower or outer Ethiopia about 12 degrees beyond the equator. Whence more recent writers have contracted this most southern parallel of the ancients by 4 and a half degrees, from which it is evident that the latitude of the inhabited Earth of the ancients was not 80 degrees, as Ptolemy thought, but only 75 degrees.

Ptolemy further reviews the celestial appearances that Marinus uses to confirm the latitude of the Earth defined by him. Having diligently examined these, he concludes that no celestial observation is brought forward by Marinus that could convince us that there is habitation beyond the equator toward the South, because no such observation can agree with even one place of southern latitude. Of these observations of Marinus, only the first is useful, which we have decided to expound. Marinus says that the Zodiac appears in its entirety in the torrid zone, and there shadows are transformed, and all stars rise and set; but the constellation of the Lesser Bear alone does not set, but appears continually above the Earth in places that are 5,500 stadia distant to the North from the equator, around the emporium of Ocelea in Arabia Felix. From this observation, it is clearly convinced how great the elevation of the pole at Ocelea is in this manner.

Let the meridian drawn through Ocelea be AEFB, and the horizon ACB, the pole of which is E, that is, the zenith of the place of Ocelea existing on the surface of the Earth at C. Let there be a star at the extreme tail of the Lesser Bear H, which in that habitation always exists above the Earth and is elevated slightly above the horizon at its minimum altitude; this star indeed receded further to the South then than other stars of the same constellation, the declination of which star is given at that age from the observations of Hipparchus as 77 degrees and 36 minutes. To this is owed the arc HI, the distance of the star from the equator FCI. The complement of this is the arc

A celestial diagram shows a circle (meridian AEFB) with a horizontal line (horizon ACB). Point E is at the top (zenith). A star labeled H is positioned on the upper left quadrant, representing the Ursa Minor star. Point I is marked on the right. Geometric lines connect H and I to center C.

HD, the distance of the aforesaid star from the pole of the world, 12 degrees and 24 minutes, and such is the arc EF, the latitude of the emporium of Ocelea. Ptolemy seems sufficiently to approve this observation, as he puts the latitude of that city in the sixth book of this volume at 12 degrees. However, the distance of this star from the pole is much smaller in this our time: for it is distant by only three and a half degrees, nor is any other star closer to the North pole today, whence for this reason it is commonly called the Polar Star.

On the eighth chapter.

Since in the preceding chapter Ptolemy had refuted the reasons of Marinus by which he strove to prove from celestial appearances that the southern limit of the inhabited Earth is produced as far as the winter tropic, he now consequently examines other reasons taken from both terrestrial and maritime journeys, by which Marinus demonstrated that the same southern limit of the entire inhabited Earth coincides with the winter tropic.

The first is indeed a terrestrial journey from Leptis Magna as far as Agisymba, from which he gathers that Agisymba is distant from the equator toward the South by 4,600 stadia, to which correspond a little more than 9 degrees, by assigning 500 stadia to one degree. Leptis Magna is a coastal city of Africa exposed to the Mediterranean Sea, which was also called Neapolis, then the ancient Tripolis of Barbary, not far from which Tripolis Nova was built.

The second is a maritime journey made from the city of Ptolemais in the Troglodytica region to the Prasum promontory, from which Marinus gathers that the Prasum promontory is distant from the Equinoctial by 27,800 stadia, to which correspond 55 degrees and 36 minutes. From this reason, it would follow that that promontory and the region of Agisymba are subject to the cold zone situated in the South, which is enclosed within the parallel of 24 degrees of southern latitude and the parallel of 66 degrees. Whence it is necessary that they have the same vigor of cold that the Scythians and Sarmatians have, who dwell under a similar zone to the North. This is false; for the region of Agisymba possesses a hot climate, as is known to all. However, Marinus himself, to avoid this inconvenience, submits that this entire number of stadia should not be taken, but half, because of the sinuosity of the navigation. This, however, is refuted by Ptolemy for this primary reason: that Marinus did not use this correction in other dimensions of journeys.

On the ninth chapter.

This entire chapter is consumed in the disapproval of some navigations assumed by Marinus to confirm that the region of Agisymba and the Prasum promontory are subject to the winter tropic. And because the text is easy in itself and contains nothing noteworthy, we shall leave these navigations considered by Marinus. Finally, at the end, Ptolemy concludes that the Prasum promontory and the region of Agisymba must be located in a similar situation on the opposite southern shore with respect to the Equinoctial, which some northern region holds, in which men are affected by a similar color, as are the inhabitants of Agisymba, and in which elephants and other animals are found, just as in Agisymba and around the Prasum promontory. This conjecture is indeed very weak, and experience often does not respond: for not only in opposite parallels is diversity found in men, in the temperature of the air, and in the produce of the Earth, but even in the same parallel, and even under the Equinoctial itself, under which all habitation is not hot and scorching. For the island of Zeilan is situated under the torrid zone between the fifth and tenth degrees of northern latitude, yet it possesses a most temperate climate, most healthy air, and most fertile land that is perpetually verdant; moreover, it even has white inhabitants. There are also other habitations conveniently under the equator and the torrid zone on islands around Eastern India and in the New World, which differ greatly from similar habitations of Africa. Whence this reasoning of Ptolemy, taken from the similarity of men, animals, the produce of the Earth, and the quality of the air, is to be utterly rejected for the construction of geography.

On the tenth chapter.

Here he confirms, by the reasoning brought to an end in the previous chapter, that the region of Agisymba and the Prasum promontory are to be located under the anti-parallel through Meroe, that is, under the parallel opposite to that which is drawn through Meroe, the island of the Nile, which falls on 16 degrees and 25 minutes. Hence, from this confirmed southern limit, he gathers that the latitude of the entire known world is not 87 degrees or 43,500 stadia, as Marinus posited, but 80 degrees and 40,000 stadia, by assigning 500 stadia to each degree.

On the eleventh chapter.

After the amendment of the latitude of the known world, about which Ptolemy has been occupied until now, he now approaches the other dimension of the Earth, namely longitude, which is indeed taken from the West to the East and is measured according to the Equinoctial circle, fifteen degrees of which make one hour. Therefore, Ptolemy says that Marinus places the longitude of the entire world at 15 complete hourly intervals, which make 225 degrees, starting from the meridian of the Fortunate Islands toward the West up to the meridian that is drawn through the Seres, the Sinae, and Cattigara to the East. He corrects and contracts this longitude, as being justly larger, into only twelve hourly intervals and 180 degrees, so that it may encompass a semicircle of the Equinoctial. Ptolemy, however, approves some of the considerations and calculations of Marinus made from the dimensions of journeys, but taxes and corrects others.

First, Ptolemy confirms that the interval between the Fortunate Islands and the city of Hierapolis, situated on the Euphrates under the parallel through Rhodes, was correctly accepted and numbered by Marinus, for the reason that it squares with the shorter and particular distances of places that have been traversed by constant journeys. However, how great this interval is and how it agrees with particular distances and places is not posited by Ptolemy, as he refers himself to the writings of Marinus.