When some hundred metres have been traversed, great difficulty in breathing begins to be experienced, the lungs feel oppressed, and every step, every movement of the body, causes great fatigue and compels the stopping to take breath. Feeble constitutions cannot endure the weariness and illness which are experienced. The reflection of the sun upon the snow is intense, for which reason the wearing of dark glasses is necessary. The face should also be veiled, to prevent the vertigo, which the white sheet surrounding the traveler produces toward the middle of the journey; when the day is fine and the atmosphere clear, the panorama is incomparably beautiful. The city of Puebla is clearly seen, and, at a greater distance the peak of Orizaba and the Cofre of Perote. There may also be seen, with all clearness, the summit of Ixtaccihuatl, totally without a crater. After some four hours of travel, the end of the journey, the summit of the volcano is reached; the last steps are particularly difficult, because the slope is now 40° and the rarity of the air is greater; progress is difficult.
From the point where the crater is reached it is not easy to take full cognizance of its depth, though the general form may be appreciated. This is elliptical; the major diameter measures some fifty metres more than the other. A crest of rock, of varying elevation, forms the edge, which makes it very irregular; it is very narrow; a simple step leads from the outer, to the inner, slope. This edge presents two heights—one is the Espinazo del Diablo (Devil’s Backbone), the other is the Pico Mayor (Greater peak), which is, as its name indicates, the highest point of the volcano, being 150 m. higher than the Espinazo. The Pico Mayor is almost inaccessible, but its summit may, with difficulty, be reached.
The major diameter of the crater corresponds to the two summits named, has some 850 m. length, and its direction is from south 20° west to north 20° east. The transverse diameter may be estimated at 750 m., which would give the crater a circumference of 2,500 m. In descending from the border, the crater presents three distinct parts; a slope of 65°, a