If on the one hand the parallels of Byzantium and Marseilles are the same, as Hipparchus asserts on the faith of Pytheas, (for he[719] says that at Byzantium the gnomon indicates the same amount of shadow as Pytheas gives for Marseilles,) and at the same time the parallel of the Dnieper is distant from Byzantium about 3800 stadia, it follows, if we take into consideration the distance between Marseilles and Britain, that the circle which passes over the Dnieper traverses Britain as well.[720] But the truth is that Pytheas, who so frequently misleads people, deceives in this instance too. It is generally admitted that a line drawn from the Pillars of Hercules, and passing over the Strait [of Messina], Athens, and Rhodes, would lie under the same parallel of latitude.[721] It is likewise admitted, that the line in passing from the Pillars to the Strait of Sicily divides the Mediterranean through the midst.[722] Navigators tell us that the greatest distance from Keltica to Libya, starting from the bottom of the Galatic Bay, is 5000 stadia, and that this is likewise the greatest breadth of the Mediterranean. Consequently from the said line to the bottom of the bay is 2500 stadia; but to Marseilles the distance is rather less, in consequence of that city being more to the south than the bottom of the bay.[723] But since from Rhodes to Byzantium is about 4900[724] stadia, it follows that Byzantium must be far north of Marseilles.[725] The distance from this latter city to Britain is about the same as from Byzantium to the Dnieper.[726] How far it may be from Britain to the island of Ierne is not known. As to whether beyond it there may still be habitable lands, it is not our business to inquire, as we stated before. It is sufficient for our science to determine this in the same manner that we did the southern boundaries. We there fixed the bounds of the habitable earth at 3000 stadia south of Meroe (not that these were its exact limits, but because they were sufficiently near); so in this instance they should be placed about the same number of stadia north of Britain, certainly not more than 4000.[727] It would not serve any political purpose to be well acquainted with these distant places and the people who inhabit them; especially if they are islands whose inhabitants can neither injure us, nor yet benefit us by their commerce. The Romans might easily have conquered Britain, but they did not care to do so, as they perceived there was nothing to fear from the inhabitants, (they not being powerful enough to attack us,) and that they would gain nothing by occupying the land. Even now it appears that we gain more by the customs they pay, than we could raise by tribute, after deducting the wages of the soldiers necessary for guarding the island and exacting the taxes. And the other islands adjacent to this would be still more unproductive.