On September 10th, returning from a reconnaissance survey of the Pampaconas River, I joined Professor Bowman’s party, Dr. Erving acting as my assistant. We crossed the Cordillera Vilcapampa and the Canyon of the Apurimac and after a week’s rest at Abancay started the topographic work near Hacienda San Gabriel south of Abancay. Working up the deep valley of Lambrama, observations for latitude and azimuth were made midway between Hacienda Matara and Caypi.

On October 4th we made our camp in newly fallen snow surrounded by beautiful glacial scenery. The next day on the high plateau, we passed sharp-crested glaciated peaks; a heavy thunder and hail storm broke out while I occupied the station at the pass, the storm continuing all the afternoon—a frequent occurrence. The camp was made 6 miles farther on, and the next morning I returned to finish the latter station. I succeeded in sketching the detailed topography just south of the pass, but shortly after noon, a furious storm arose similar to the one the day before, and made further topographic work impossible; to get connection farther on I patiently kept my eye to the eye-piece for more than an hour after the storm had started, and was fortunate to catch the station ahead in a single glimpse. I had a similar experience some days later at station 16,079, Antabamba Quadrangle, on the rim of the high-level puna, the storm preventing all topographic work and barely allowing a single moment in which to catch a dim sight of the signals ahead while I kept my eye steadily at the telescope to be ready for a favorable break in the heavy clouds and hail.

At Antabamba we got a new set of Indian carriers, who had orders to accompany us to Cotahuasi, the next sub-prefectura. Raimondi’s map indicates the distance between the two cities to be 35 miles, but although nothing definite was stated, we found out in Antabamba that the distance was considerably longer, and moreover that the entire route lay at a high altitude.

From the second day out of Antabamba until Huaynacotas was in sight in the Cotahuasi Canyon, a distance of 50 miles, the route lay at an altitude of from 16,000 to 17,630 feet, taking in 5 successive camps at an altitude from 15,500 to 17,000 feet; 12 successive stations had the following altitudes:

16,379feet
16,852"
17,104"
17,559"
17,675"—highest station occupied.
17,608"
17,633"
16,305"
17,630"
17,128"
16,794"
16,260"

The occupation of these high stations necessitated a great deal of climbing, doubly hard in this rarefied air, and often on volcanoes with a surface consisting of bowlders and ash and in the face of violent hailstorms that made extremely difficult the task of connecting up observations at successive stations.

At Cotahuasi a new pack-train was organized, and on October 25th I ventured to return alone to the high altitudes in order to continue the topography at the station at 17,633 feet on the summit of the Maritime Cordillera. Dr. Erving was obliged to leave on October 18th and Professor Bowman left a week later in order to carry out his plans for a physiographic study of the coast between Camaná and Mollendo. Philippi Angulo, a native of Taurisma, a town above Cotahuasi, acted as majordomo on this journey. Knowing the trail and the camp sites, I was able to pick out the stations ahead myself, and made good progress, returning to Cotahuasi on October 29th, three or four days earlier than planned. From Cotahuasi to the coast I had the assistance of Mr. Watkins. The most trying part of the last section of high altitude country was the great Pampa Colorada, crowned by the snow-capped peaks of Solimana and Coropuna, reaching heights of 20,730 and 21,703 feet respectively. The passing of this pampa took seven days and we arrived at Chuquibamba on November 9th. Two circumstances made the work on this stretch peculiarly difficult—the scarcity of camping places and the high temperature in the middle of the day, which heated the rarefied air to a degree that made long-distance shots very strenuous work for the eyes. Although our base signals were stone piles higher than a man, I was often forced to keep my eye to the telescope for hours to catch a glimpse of the signals; lack of time did not allow me to stop the telescope work in the hottest part of the day.

The top of Coropuna was intersected from the four stations: 16,344, 15,545, 16,168, and 16,664 feet elevation, the intersections giving a very small triangular error. The elevation of Mount Coropuna’s high peak as computed from these 4 stations is:

21,696 feet
21,746 "
21,714 "
21,657 "
Mean elevation 21,703 feet above sea level.