But their troubles were not yet over. The sea was still very rough, "for the winter of that country was setting in," and even the pilot suggested turning back to take refuge for a time. When Vasco da Gama heard of turning backward he cried that they should not speak such words, because as he was going out of the bar of Lisbon he had promised God in his heart not to turn back a single span's breadth of the way, and he would throw into the sea whosoever spoke such things. None could withstand such an iron will, and they struggled on to Mossel Bay, already discovered by Diaz. Here they landed "and bought a fat ox for three bracelets. This ox we dined off on Sunday; we found him very fat, and his meat nearly as toothsome as the beef of Portugal"--a pleasant meal, indeed, after three months of salted food. Here, too, they found "penguins as large as ducks, which had no feathers on their wings and which bray like asses." But there was no time to linger here. They sailed onwards till they had passed and left behind the last pillar erected by Diaz, near the mouth of the Great Fish River. All was new now. No European had sailed these seas, no European had passed this part of the African coast. On Christmas Day they found land to which, in commemoration of Christ's Nativity, they gave the name of Natal. Passing Delagoa Bay and Sofala without sighting them, Vasco da Gama at last reached the mouth of a broad river, now known as Quilimane River, but called by the weary mariners the River of Mercy or Good Tokens. Here they spent a month cleaning and repairing, and here for the first time in the history of discovery the fell disease of scurvy broke out. The hands and feet of the men swelled, their gums grew over their teeth, which fell out so that they could not eat. This proved to be one of the scourges of early navigation--the result of too much salted food on the high seas, and no cure was found till the days of Captain Cook. Arrived at Mozambique--a low-lying coral island--they found no less than four ocean-going ships belonging to Arab traders laden with gold, silver, cloves, pepper, ginger, rubies, and pearls from the East. [Illustration: AFRICA AS IT WAS KNOWN AFTER DA GAMA'S EXPEDITIONS. From Juan de la Cosa's map of 1500.]