From the days when the Phoenician sailors groped along the coasts of the Mediterranean, in the early dawn of civilisation, up to the present time, explorers have ever forged their way across unknown seas and through dark forests — sometimes Slowly, and with centuries of intermission, at other times with giant strides, as when the discovery of America and the great voyages round the world dispersed clouds of ignorance and prejudice even in reference to the globe itself.