The American Isthmus extends in length about twelve hundred miles, from the Coazacoalcos River, in Mexico, to the valley of the Atrato, in Columbia. It includes the Mexican States of Tehuantepec, the Republics of Yucatan, Guatemala, Belize, Honduras, San Salvador, Nicaragua, Costa Rica, the Mosquito Kingdom, and the State of Panama, one of the States of Columbia. Embracing a varied and salubrious climate; a rich soil, clothed with the luxuriance of tropical vegetation; ruins of an ancient people, consisting of vast and silent cities, whose impressive but grotesque architecture, embodying a civilization unique and insular, is overgrown with forest of flor de robles, mahogany, and palm; divided throughout its entire length by a volcanic dyke, rising to altitudes of five to six thousand feet, and sinking into depressions two hundred and eighty feet above the level of the sea; concealing in its strata the matrices of gold and precious stones; expanding in Yucatan to a width of six hundred and fifty miles, and contracting at San Blas and Darien to thirty or forty miles—this connecting link, the result of a submarine endogenous movement subsequent to the elevation of the continents which it unites, opposes a solitary but not insurmountable barrier to the commercial union of the two oceans. The narratives of Dampier, Wafer, the adventures of the Spanish Buccaneers who infested the South Sea, and the descriptions of Las Casas, Fonseca, Don Andres de Ariza, however interesting historically, add but little to the physico-geographical knowledge of the country. These histories contain accounts of earthquakes as terrific as that which has recently visited the coast; of sieges notable for bold assault and gallant defense; of gold mines opened and abandoned; of strange fauna, birds of splendid plumage, and a tropical flora of gorgeous colors; but the reader will seek in vain for information of practical value in determining the question of a practicable route for an interoceanic ship canal. Recent explorers have supplied much accurate information of special routes. The following table exhibits the different projects for uniting the Atlantic and Pacific: