We are also indebted to Eratosthenes for the first regular parallel of latitude, and also for tracing a meridian.  His parallel of latitude began at the Straits of Gibraltar, and passed eastward through Rhodes to the mountains of India; the intermediate places being carefully set down.  His meridian line passed through Rhodes and Alexandria, as far as Syene and Meroe.  Meroe, on this account, became an object of the greatest interest and importance to all the succeeding ancient geographers and astronomers, and they have taken the utmost labour and care to ascertain its latitude accurately.  Strabo informs us, that Eratosthenes constructed a map of the world; but he does not give such particulars as will enable us to trace the extent of his geographical knowledge.  At the extremity of the world to the east, bounded by the ocean, Thina was placed in the map of Eratosthenes, in the parallel of Rhodes; a parallel which passes through the empire of China, within the Great Wall.  Eratosthenes, according to Strabo, (to whom we are indebted for nearly all we know respecting this philosopher,) asserts that Thina had been, previously to the construction of his map, incorrectly placed in the more ancient maps.  His information respecting Meroe or Abyssinia, is most probably derived from Dalion, Aristocreon, and Bion, who had been sent by Ptolemy Philadelphus and his successors into that country, or from Timosthenes, who sailed down the coast of Africa as low as Cerne.  His information on the subject of India (which, however, as far as regards oriental commerce, is very confused) must have been derived from the Macedonians.  There is little doubt that the library of Alexandria afforded him access to all the knowledge which then existed respecting the various countries of the globe; but the turn of his mind led him rather to astronomical than geographical studies; or rather, perhaps, he directed his labours and his talents to the discovery of the figure and circumference of the earth, thinking, that till this was effected, the delineation of the habitable world, and the relative position of different countries, must be very inaccurate as well as incomplete.  This opinion regarding Eratosthenes, that he was more of a geometrician than a geographer, seems to be confirmed by the testimony of Marcian of Heraclia, who informs us, that Eratosthenes took the whole work of Timosthenes, preface and all, as it stood, and in the very same words.  If this account be accurate, it is probable that Eratosthenes’ knowledge of Thina, and his being able to correct the erroneous position of this country in more ancient maps, was derived from Timosthenes, who had commanded the fleet of Ptolemy Philadelphus on the Indian Ocean.