enduring monument to his industry and talent; but there is necessarily a great deal of it that was altogether transitory in its character both on account of the political and social revolution which has since occurred, and in consequence of the opening, by the republic, of Mexican ports to the commerce of the world.
Nevertheless, at the period of Humboldt's visit, the main bold geographical and geological features of Mexico were sufficiently well known for practical purposes, and as his descriptions have, in most cases, stood the test of criticism during near half a century, we may still safely appeal to him, and to his industrious countryman, Muhlenpfordt,1 as the most reliable authorities upon these topics.
According to Humboldt, Mexico presented a surface of one hundred and eighteen thousand four hundred and seventy-eight square leagues, of twenty-five to the degree, yet this calculation did not include the