Their object has been a puzzle. They were not watch-towers from the positions of many of them; not fortresses, not dwellings, not temples, not tombs, for no bones are found. I believe that Dr. Guillemard, whose excellent descriptions of the Minorcan prehistoric remains I have been quoting, has hit upon the right solution. The fields are covered with stones, and one of the principal occupations of the husbandman is to clear the stones off the cultivable land. In modern times they make stone walls, for something has to be done with them. Dr. Guillemard holds that the _talayuts_ are the stones cleared from the fields by the ancient people. They built these very solid towers with them, which served to house pigs and sheep at night; perhaps also as a look-out place, where their positions would serve such a purpose. But clearing the fields of stones was the primary object. The Minorcan builders of stone temples, tombs, and dwellings, and pilers up of stones were prehistoric beyond any doubt, and may have worked and worshipped them four thousand years ago. The Phœnicians probably found their descendants on the island, and they became subject to the Semitic traders and their Carthaginian offshoots, who held the Balearic Islands while they were dominant in Spain. Minorca was best known as possessing the most capacious and safest harbour in the Mediterranean, and its name of Port Mahon makes the giver of that name an important factor in the story of the island. Mago was the youngest son of Hamilcar Barca, and when he first began to serve under his brother Hannibal in Italy, in B.C. 218, he must have been very young; but his capacity and fitness for command were soon realised by the great general. Mago was given command of the cavalry, and led his troops across the river Po, each man swimming by the side of his horse. Mago did distinguished service at the battle of Trebia, and was by his brother’s side at Cannæ. He was then detached to reduce Samnium and the Bruttii. In about B.C. 212 he was sent to reinforce his other brother, Hasdrubal, in Spain. It was a losing cause, for the Carthaginians vainly opposed the victorious career of Scipio. The brothers resisted long. At last they were hopelessly defeated by Scipio at a place called Silpia, apparently in the Sierra Morena. Mago long held out at Gades. Here he received orders to collect troops and ships, and to make a diversion by landing at Genoa and transferring the seat of war to Italy. Having diligently assembled troops and the means of transport, he left Spain for ever and made sail, shaping a course, in compliance with his instructions, from Carthage. Mago wintered in the splendid harbour at the eastern end of Minorca, which has ever since borne his name--Portus Magonis, corrupted into Port Mahon.