Note 6 — Chapter II · FORM, STRUCTURE, AND COMPOSITION OF VOLCANIC MOUNTAINS.
Reading edition
Whymper determined the height to be 20,498 feet; Reiss and Stübel make it 20,703 feet. Whymper thinks there may be a crater concealed beneath the dome of snow.—Travels amongst the Great Andes of the Equator, by Edward Whymper (1892).