crowned with success, and they dropped exhausted on the brink of the crater.
"The crater is nearly circular and variously estimated by different members of our troop at from 400 to 650 yards in diameter. We all estimated the depth at 300 feet. The sides are nearly vertical, and show strong and unmistakeable signs of fire, looking like the mouth of a gigantic furnace.
"At the foot of this perpendicular wall was quite a bank of sand or débris, which had fallen from the inner surface of the rock, indicating the great length of time since the volcano had been extinct. Indeed its fires were perfectly dead, for the bottom of the crater was covered with snow. Humboldt says its most violent eruptions were in 1545 and 1566,—nor have I seen a record of an eruption since.
"As I desired to test Humboldt's altitude, I had taken the precaution to be as well prepared as circumstances would admit, and accordingly had carried with me the best barometer I could get, which, from previous calculations, I deemed capable of indicating a height of from 300 to 400 feet higher than that given by him. I had, also, provided myself with a spirit-lamp and thermometer, for the purpose of taking the temperature of boiling water; but, on the march, the bottle containing the alcohol was broken and the spirit entirely lost. I therefore determined to test the combustible qualities of whiskey. One of my first objects after reaching the summit was to make observations; but, on preparing the barometer, the mercury sank at once below the graduation.
"I estimated the distance between the lowest line of graduation and the top of the mercury at two-tenths of an inch, which gives,—with corresponding observations in the city of Orizaba at the same hour,—an elevation of 17,907 feet, and makes it the highest point on the North American Continent. I do not think I could have been far wrong in my estimate, as the means of comparison were before me; but, even supposing I was mistaken one-twentieth of an inch, we still have an elevation of 17,819 feet, 98 feet higher than Popocatepetl, which is usually considered the highest point,—5,400 metres, or, 17,721 feet, as given by Humboldt.[1] The temperature was just below freezing point. My attempt to burn whiskey failed. Since my return to the United States, I have observed that Humboldt states that Mr. Ferrar measured Orizaba, eight years before his arrival in Mexico, and gave the mountain an elevation of 5,450 metres or 17,885 feet. Humboldt's measurement, made from a
- ↑ It will be seen hereafter that expeditions subsequent to Humboldt's calculation give Popocatepetl a height of 17,884 feet.
