in the latitude of 42° (Boston or New York) would have given the country an almost Arctic character; but under the Tropic of Cancer, or in latitudes 18° to 25° north, the climate at these high elevations is almost that of perpetual spring. At these high elevations of the Mexican plateau furthermore, the atmosphere is so lacking in moisture, that meat, bread, or cheese, never molds or putrefies, but only spoils by drying up. Perspiration, even when walking briskly in the middle of the day, does not gather or remain upon the forehead or other exposed portions of the body; and it is through this peculiarity only of the atmosphere that the city of Mexico, with its large population, and its soil reeking with filth through lack of any good and sufficient drainage, has not long ago been desolated with pestilence.
The border States of Mexico on the north are Sonora, Chihuahua, Coahuila, and Tamaulipas. Sonora is larger than the States of Ohio and Indiana combined; Chihuahua is nearly as large as New York and Pennsylvania: Coahuila is larger than New York; and Tamaulipas is nearly as large as Maryland, New Jersey, Connecticut, and Massachusetts combined.
The surface of the great Mexican plateau, or table-land, although embracing extensive areas of comparatively level surface, which are often des-
