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 5,460 metres or 17,885 feet. Humboldt's measurement, made from a plain near Jalapa, is 155 metres less, or 17,377 feet in all. It will be seen that my determination agrees very nearly with that of Mr. Ferrar.