The elevation of Coropuna as derived from these four stations has thus a mean error of 18 feet (method of least squares) while the elevation of each of the four stations as carried up from mean sea level through 25 stations—vertical angles being observed in both directions—has an estimated mean error of 30 feet. The result of this is a mean error of 35 feet in Coropuna’s elevation above mean sea level.
The latitude is 15° 31′ 00″ S.; the longitude is 72° 42′ 40″ W. of Greenwich, the checking of these two determinations giving a result unexpectedly close.
On November 11th azimuth and latitude observations were taken at Chuquibamba and two days later we arrived at Aplao in the bottom of the splendid Majes Valley. In the northern part of this valley I was prevented from doing any plane-table work in the afternoons of four successive days. A strong gale set in each noon raising a regular sandstorm, that made seeing almost impossible, and blowing with such a velocity that it was impossible to set up the plane-table.
From Hacienda Cantas to Camaná we had to pass the western desert for a distance of 45 miles. We were told that on the entire distance there was only one camping place. This was at Jaguey de Majes, where there was a brook with just enough water for the animals but no fodder. Thus we faced the necessity of carrying water for ten men and fodder for 14 animals in excess of the usual cargo; and we were unable to foretell how many days the topography over the hot desert would require.
Although plane-table work in the desert was impossible at all except in the earliest and latest hours of the day, we made regular progress. We camped three nights at Jaguey and arrived on the fourth day at Las Lomas.
The next morning, on November 23rd, at an elevation of 2178 feet near the crest of the Coast Range, we were repaid for two months of laborious work by a glorious view of the Pacific Ocean and of the city of Camaná with her olive gardens in the midst of the desert sand.
The next day I observed latitude and azimuth at Camaná and in the night my companion and assistant Mr. Watkins and I returned across the desert to the railroad at Vitor.
Conclusions
The planned methods were followed very closely. In two cases only the plane-table had to be oriented by the magnetic needle, the backsights not being obtainable because of the impossibility of locating the last station, passing Indians having removed the signals.
In one case only the distance between two stations had to be determined by graphic triangulation exclusively, the base signals having been destroyed. Otherwise graphic triangulation was used as a check on distances.