visible at Mexico and Cholula, and the second at Cholula and Vera Cruz, served me to verify the meridian difference of the city of Mexico and the port of Vera Cruz by a method very advantageous, but hitherto little followed; that of perpendicular bases, azimuths, and angles of altitude*. The city of Mexico is nearer by one half to the two Nevados de la Puebla than the cities of Bern and Milan are to the central chain of the Alps. This great proximity contributes much to give an awful and majestic aspect to the Mexican vol canos. The contours of their summits, covered with eternal snow, appear so much the more marked, as the air through which the eye receives the rays is more rare and transparent. The show is of a most extraordinary brilliancy, particularly when it descends from a sky of which the blue is always deeper than that of the sky which we see from our plains of the temperate zone. The observer finds himself, in the city of Mexico, in a stratum of air, whose barometrical pressure is only 585 millimetres †. It is easy to conceive, that the extinction of light must be very trifling in an atmosphere so little condensed, and that the summit of the Chimborazo, or the Popocatepetl, seen from the plains of Riobamba or Mexico, must exhibit * See above, p. xxiii. and my Recueil d'observations astronomiques, vol. I. p. 373. + Nearly twenty-three inches. Trans. more distinct contours than if they were seen at the same distance from the shores of the ocean. The Iztaccihuatl and the Popocatepetl, of which the latter has the conical form peculiar to the Cotopaxi and the Peak of Orizaba, are called indistinctly in the country the volcanos of la Puebla or Mexico, because they are equally well distinguished from these two cities. I have no doubt that the Iztaccihuatl, which Cardinal Lorenzana calls Zihualtepec, is an extinguished volcano; but no Indian tradition goes back to the time when this mountain, which in its contours resembles the volcano of Pichincha, vomited forth fire. The same observation applies to the Nevado de Toluca. The Spaniards have been in the habit, from the first times of the conquest, of naming every insulated summit volcan, which enters into the region of perpetual snow. The words Nevado and Volcan are frequently confounded: I have even heard at Quito, the strange expressions Volcan de Nieve and Volcan de Fuego*. The Cotopaxi, for example, is reputed a fire-volcano, because its periodical eruptions are known, while the Corazon and the Chimborazo are called snow-volcanos, because the natives suppose that the fire is concealed in them. In the kingdom of Guatimala †, and in the Philip * Snow-volcano and fire-volcano. Trans. +"En Goatemala hay dos volcanos, uno de fuego y otro de agua." (Lorenzana, in a note to the Letters of Cortes.) pine Islands, they call water-volcanos (volcanes de agua) those which inundate the surrounding coun try. From these examples, we may see that the word volcan, in Spanish maps, is frequently used in a sense quite different from what is understood by it among the other nations of Europe. M. Don Luis Martin drew the volcanos of la Puebla as they appear in a clear day from the Terrace of the School of Mines-(Seminario Real de Mineria). A justly celebrated artist, who honours me with a particular friendship, M. Gmelin of Rome, was obliging enough to retouch the drawing of M. Martin, and my sketch of the Pic d'Orizaba. The contours were nowise altered, and I have no doubt that the hand of a great master will easily be perceived in the distribution of shade, as well as in the effect of the chiaro scuro. It may be useful to observe, that the volcanos of la Puebla were drawn in the month of January, in a season when the inferior limit of perpetual snow almost descended to the height of the summit of the Peak of Teneriffe, or to 3800 metres of absolute elevation *. During my stay at Mexico, I saw such immense falls of snow in the mountains, that the two volcanos were almost united by one band of snow. The maximum † of elevation of the region of snow, which I found in the * About 12460 feet. Trans. + See book i. cap. ii. month of November 1803, was nearly 4560 metres *. The Sierra Nevada, or Iztaccihuatl, is only a few metres higher than Mount-Blanc; but the Popocatepetl surpasses Mount-Blanc 625 metres† in height. Besides, the plain which extends from the city of Mexico to the foot of the volcanos is itself more elevated than the summit of Mountd'Or, and the famous passages of the lesser St. Bernard, Mount Cenis, Simplon, and the ports of Gavarnie and Cavarere. It was between these two volcanos of la Puebla that Cortes passed with his troop and six thousand Tlascaltecs, on his first expedition against the city of Mexico. During this severe march, the valorous Diego Ordaz, to give the natives a proof of his courage, attempted to reach the summit of the Popocatepetl. Though he did not succeed in his undertaking †, the emperor Charles V. gave him permission to enter a volcano in his coat of arms. I will not now agitate the question which is so often the subject of dispute at Mexico, namely, whether Francisco Montaño, after the taking of the capital, in 1552, drew the sulphur employed in the fabrication of powder from the 14956 feet. Trans. † 2050 feet. Trans. Cartas de Cortes, p. 318 and 380; Clavigero, III. p. 68, „and 162. crater of Popocatepetl, or from some lateral crevice. X. PICTURESQUE VIEW OF THE PIC D'ORIZABA. The Pic d'Orizaba, on the position of which Mr. Arrowsmith and other geographers have thrown so much confusion in their maps, is as celebrated among navigators as the Pic of Teneriffe, the Silla of Caraccas, the Table Mountain, or the Pic S. Elie. I have drawn it as it appears in the road from Xalappa to the village of Oatepec (Huatepeque), near the Barro de Santiago. From this station nothing is discovered but the part which is covered with perpetual snow. The first plane of my drawing is a thick forest of liquidambar styraciflua, melastomes, strawberry trees, and pipers. It is very remarkable that the two largest Mexican volcanos, the Popocatepetl and the Citlaltepetl, have both the crater inclined to the south-east. We find in general, that in the equinoxial region of New Spain the mountains decline most rapidly towards the gulf of Mexico, and that the ridges of rocks are most frequently directed from the N. W. to the S. E. For the better distinction of active from extinguished volcanos, I have ventured to add a small column of smoke to the drawings of the Pic d'Orizaba and the great volcano of Puebla, though I never observed any smoke either from |