were often violently precipitated either against masses of rocks, or to the very verge of precipices, from which they only saved themselves by the firmness of their nerves and the strength of their iron-shod staves. At length, however, after several very narrow escapes, they reached the limit of the forest, and in a few days returned to Mexico in excellent spirits.
By the failure of the Indians to ascend with them to the summit, they were unable to make many experiments, for which the great scientific acquirements of Mr. Von Gerolt so highly qualify him. In addition to this, the barometer, which had been slung on the back of Mr. Egerton's servant, was broken by a fall; so that (as far as measurements were concerned,) the expedition was entirely fruitless. I have, however, compiled from the notes of two other parties, the following statements, which are interesting, as affording the most accurate dimensions of this remarkable volcano:
| Mr. Berbeck, who ascended on the 10th of November, 1837, gives the elevation of Popocatepetl, above the Valley of Mexico, at | 10,382 | feet. |
| Mexico is above Vera Cruz, according to Humboldt, | 7,470 | |
| Whole height of volcano above the sea, | 17,852 | |
| | ||
| Mr. Glennie, who ascended 20th April, 1887, gives the elevation of Popocatepetl, above the Valley of Mexico, at | 10,413 | feet. |
| Mexico above Vera Cruz, according to Humboldt, | 7,470 | |
| 17,883 | ||
| | ||
| By a series of observations, made at Vera Cruz in 1828, the opinion is, that the true height of Mexico above Vera Cruz, or in other words, above the level of the sea, is 7,548 feet, which, added to their elevations above the Valley of Mexico, will give us, for | ||
| Berbeck, | 17,980 | feet. |
| Glennie, | 17,961 | |
| While Humboldt, (who gives his by trigonometrical observations,) | 17,715 | |
| The limit of all vegetation, according to Glennie, is | 12,698 | |
| Pico del Fraile, | 16,895 | |
| Limit of pines, | 12,544 | |
| | ||
| In November, 1827, the thermometer, at the summit, was 22° of Fahr. and in April of the same year, 33°. | ||
| | ||
| At the limit of vegetation, Mr. Von Gerolt found, at 6 p. m., the precip: of moisture, by Daniell's hygrometer, 36° Fahr. on the interior thermometer; and at 50° in the atmosphere. Water boiled at 194° Fahr. Barometer, 19.12, English. Temperature, 48° Fahr. Corresponding observations, made in Mexico, gave 23,071 English inches, from which we deduce a height of | 5,144 | English feet. |
| To which add | 7,548 | |
| 12,692 | ||
