In their search for the most lucrative beaver grounds they crossed the boundless prairies, and stimulated by the prospect of riches and the excitement of new scenes they sought the innermost recesses of the mountain wilderness, slaying what opposed their way, taking beaver by thousands and tens of thousands, and sending pack upon pack by way of St. Louis to the waiting markets of the Old World. The early returns may be estimated from the success of one enterprising man who, having employed a band of expert trappers, came out of the far regions on one occasion with nearly two hundred packs, each worth in St. Louis about one thousand dollars. In one period of two and one-half years, over six hundred thousand beaver skins were sent out by one of the great companies that were organised systematically to prosecute the fur business in North America.[2] Thus it was that the beaver became responsible for the first opening of the great western Unknown, and in order fully to understand the interesting story of human endeavour, it is necessary to glance at the characteristics of this remarkable creature, which unwittingly performed such a prominent part in affairs so momentous to the American Republic and to the world, and which in consequence has become almost extinct. By it was the trapper and trader led from the Mississippi to the Western Ocean, and from the Gila River to and beyond the bounds of Canada. With so great regularity was the daily life of the beaver ordered that the hunters in their admiration ascribed to it mental qualities which probably it did not actually possess, yet it certainly executed well defined works with skill and precision, and performed many acts which might easily have been the result of mental processes.[3] A house builder and an engineer, it constructed for its occupation comfortable lodges, it excavated canals for its convenience, and formed ponds and lakes of considerable extent by means of dams made of trees, sticks, mud, and stones. Moreover, the trees were felled by its own efforts, and cut up into pieces suitable for the object desired. The mud and stones were then combined with these pieces with a dexterity that was astonishing and that will always command for this amphibious, burrowing creature of the genus _Castor_ a high rank in the animal world. Its paws were supplied with long, strong claws, the hind ones having an extra claw peculiar to the beaver. The front pair were small and were used deftly like human hands; and the animal could walk erect on its hind feet carrying small stones and earth, pressed against the throat, for house or dam building; it could drag poles and sticks in the same manner. When necessary to move larger stones they pushed them along, sometimes using the tail also, and stones of five or six pounds' weight were moved in this way. All their works were of the same general character, and in each class they did not vary their methods, which were largely dictated by surrounding conditions.