His instructions gave him absolute freedom of action. The chief purpose of this expedition was a scientific one. Professional draughtsmen were appointed to accompany the _Heemskerk_ and make careful maps of everything that should be discovered. Special attention must be paid to the currents of the ocean and to the prevailing direction of the wind. Furthermore, a careful study of the natives must be made. Their mode of life, their customs, and their habits must be investigated, and they must be treated with kindness. If the natives should come on board and should steal things, the Hollanders must not mind such trifles. The chief aim of the expedition was to establish relations with whatever races were to be discovered. Of course there was little hope of finding anything except long-haired Papuans, but if by any chance Tasman should discover the unknown southland and find that this continent contained the rumored riches, he must not show himself desirous of getting gold and silver. On the contrary, he must show the inhabitants lead and brass, and tell them that these two metals were the most valuable commodities in the country which had sent him upon his voyage. Finally, whatever land was found must be annexed officially for the benefit of the Estates General of the Dutch Republic, and of this fact some lasting memorial must be left upon the coast in the form of a written document, well hidden below a stone or a board planted in such a way that the natives could not destroy it. On the nineteenth of August, Tasman and his two ships went to Mauritius, where the tanks were filled with fresh water and all the men got a holiday. They were given plenty of food to strengthen them for the voyage which they were about to undertake through the unknown seas. After a month of leisure the two ships left on the sixth of October of the year 1642 and started out to discover whatever they might find. The farther southward they got the colder the climate began to be. Snow and hail and fog were the order of the day. Seals appeared, and everything indicated that they were reaching the Arctic Ocean of the Southern Hemisphere. Day and night they kept a man in the crow's-nest to look for land. Tasman offered a reward of money and rum for the sailor who should first see a light upon the horizon, but they found nothing except salt water and a cloudy sky.