Speaking of the Indians, (Pueblos,) on the Rio Grande, Mr. Calhoun says, “These people can raise immense quantities of corn and wheat, and have large herds of sheep and goats. The grazing for cattle generally is superior.” (p. 206.) Of the more western Pueblos, he says, they have “an extent of country nearly four hundred miles square”;--more than twenty times as large as Massachusetts;--“they have rich valleys to cultivate, grow quantities of corn and wheat, and raise vast herds of horses, mules, sheep, and goats, all of which may be immensely increased by properly stimulating their industry, and instructing them in the agricultural arts.” (p. 215.) I might cite much more from the same authority, to the same effect; but I do not refer to Mr. Calhoun so much for the purpose of showing the agricultural capabilities of New Mexico, as of asking why Mr. Webster did not quote from this recent official work, which has been lying on the tables of members for months, instead of quoting descriptions from military officers respecting a country which he well knew they had never seen? There is good reason to believe that there are wide tracts of fertile land lying between the Sierra de los Mimbres and the Sierra Nevada, on the east and west, and the 32d and 35th degrees of latitude. The waters at the mouth of a river give no doubtful indication respecting the country from which they flow. If the volume be large, we know it must drain an extensive region; for the waters of a great river cannot be supplied from a narrow surface. So if the water be muddy, as is said to be the case with that of the Colorado, it is proof that it courses through a diluvial country. But however this may be, all accounts concur in representing New Mexico to be rich in mines; and mines are the favorite sphere for slavery, as the ocean is for commerce. In his late speech in the Senate, Mr. Davis, of Massachusetts, said, that however it might be with regard to employing slaves in New Mexico for raising crops of corn or cotton, there was still one purpose to which they might be applied,--the most odious of all purposes,--to raising crops from themselves. From this “Southern Hive,” the markets of Texas and Louisiana might be supplied with “vigintial” crops of human beings. It will be incumbent on Mr. Webster to invent some new “physical” law to meet this astute suggestion of his colleague. “Asiatic scenery” will hardly answer his purpose here. Within the limits of the proposed territory of New Mexico, it is said, on the authority of Humboldt, that that powerful and comparatively civilized people, the Aztecs, once resided. Can any person for a moment believe that the Aztecs ever grew to opulence and power, in any such sterile and desolate region, as Mr. Webster’s “diligent reading” portrays?