For bold mariners to be stopped in their advance, winds and currents must have been invariably contrary and irresistible. The stronger the belief in the universality and absolute constancy of the _trade winds_ in these regions, the more was this action attributed to them. But the investigations which have been carried on in the interests of science, the writings of Commander Maury, and the charts of Captain Kerhallet, have taught us that the variable winds due to the _cloud-ring_ extend over almost twenty degrees in the maritime area in question. We know, moreover, that every year the _monsoon_ drives back the trade winds and blows beyond the Sandwich and Tahiti Islands, so that instead of the winds being contrary, they are, for many months, very favourable for ships sailing eastward. Considerations drawn from currents lead almost to the same conclusions. In the Pacific, the equatorial current running from east to west forms in reality two great distinct oceanic streams separated by a large counter current flowing in the reverse direction. The latter skirts almost the whole northern portion of the Polynesian area; it thus, as it were, forms the outlet from the Indian Archipelago. There is every indication of its having played some part in the history of the dispersion of races in all parts of Oceania and to the east of the Malay peninsula. Finally, we know that there is no absolute regularity in the atmospheric phenomena in the regions of the Pacific, any more than elsewhere. This ocean has in common with others its typhoons and its tempests, which suddenly change the direction of the winds and carry ships before them in spite of currents. Islands, both large and small, with which it is beset, must often have been visited by sailors who had thus lost their way, of which we shall presently quote examples. Far from being _impossible_, the peopling of Polynesia by navigators starting from the Indian Archipelago is relatively _easy_ at certain times of the year, provided only that the navigators are courageous and not afraid of losing sight of land. Now we know the character of the Malay populations in this respect. Again, those who have taken all these circumstances into consideration, Malte-Brun, Homme, Lesson, Rienzi, Beechey, Wilkes and others, have not hesitated to regard Polynesia as having been peopled by migrations advancing from west to east. III. Writers, on the contrary, who have only consulted the imperfect knowledge which we till lately possessed of these seas, and the ordinary direction of the winds, have either believed in autochthony or have invented various theories to explain the presence of man in this multitude of islands and remote islets.