Baird, in his general report upon mammals, uses the following language, which is appropriate in this connection: "The beaver once inhabited all of the globe lying in the northern temperate zone; yet from Europe, China, and all the eastern portion of the United States, it has been entirely exterminated, and a war so universal and relentless has been waged upon this defenceless animal, his great intelligence has been so generally opposed by the intelligence of man, it has seemed certain, unless some kind providence should interpose, that the castor, like its congener, the Castorides, would soon be found only in a fossil state. "Happily that providence did interpose, through a certain ingenious somebody, who first suggested the use of silk in the place of fur for the covering of hats. The beaver were not yet exterminated from Western America, and now, since they are not "worth killing," in those inhospitable regions, where there is no encouragement for American enterprise or cupidity, we may hope that the beaver will there retain existence, in a home exclusively their own. "The price of beaver skins has so much diminished that they were offered to some of the party at twenty-five cents by the bale." Carson had pursued the business of trapping for eight years, and his life had been one of unceasing toil, of extreme hardship, full of danger, yet withal full of interest. More than this, while the lack of early scientific training had prevented him from making that record of his travels, which would have given the world the benefit of his explorations, he had treasured in his memory the knowledge of localities, of their conditions, and seasons, and advantages, which in the good time coming, would enable him to associate his labors with another, who possessed the scientific attainments which Carson lacked, and who with Carson's invaluable assistance would come to be known world wide as a bold explorer, and who, but for Carson's experience, where such experience was a chief requisite to success, might have failed in his first efforts in the grand enterprise entrusted to him. Carson knew the general features of the country, its mountains, plains, and rivers, and the minor points of animal and vegetable productions, from the head waters of the "monarch of rivers," to the mouth of the Colorado, and from the southern Arkansas to the Columbia, better, perhaps, than any one living, though yet but twenty-five years of age.