GREAT WALL OF PERU — SHIPPEE 469 



by the labors of Dr. Hiram Bingham. The site is magnificent- 

 above " a stupendous canyon whose rim is more than a mile above the 

 river * * * whose precipices are frequently a thousand feet 

 sheer." ^ An incomparable view of the Inca citadel is obtained from 

 the air (pi. 7. fig. 2, and pi. 8, fig. 1). 



Another day was spent in photographing Fort Sacsahuaman on 

 the heights above Cuzco, but perhaps the most interesting of our 

 aerial photographs in this region are those of the group of amphi- 

 theaters that we came upon in the Maras Pampa about 15 miles 

 northwest of Cuzco (pi. 9, fig. 1). The priests in a church in Cuzco 

 knew of their existence and said they had been used by the Incas 

 for religious presentations during their fiestas. We have, however, 

 not been able to find any mention of them in the literature on the 

 region. 



SURVEY OF THE TALARA OIL FIELDS 



Our aerial survey of the holdings of the International Petroleum 

 Co. at Talara, northern Peru, was made in February. It seemed 

 to us that the flat, desert country of the Talara fields would be easy 

 to map from the air. Certainly little correction would be nec- 

 essary in assembling a mosaic from the photographs. Several 

 problems cropped up, however, when the work began : How best to 

 cover the area with ground control ; how best to give some relief to 

 the mosaic, to make depressions look like depressions, and oil rigs 

 stand out as other than mere dots on the sand. Clouds also hindered 

 us, since to cover the extensive area economically we had to fly at 

 15,000 feet, and even on the arid Peruvian coast there are few really 

 cloudless days. 



For ground control, in addition to Avhite lime markers at ail our 

 triangulation points, we made use of a system developed by Johnson 

 several years ago in which a network of oblique sheets is used to tie 

 in various landmarks so that in making the mosaic for the vertical 

 photographs each point can be definitely aligned. By flying late in 

 the afternoon and for short periods only we utilized the shadows cast 

 by the oil rigs and thus obtained a remarkably realistic picture of the 

 fields. 



The Talara engineers, because of previous experience with a care- 

 less job of aerial mapping, were frankly skeptical of the accuracy of 

 our work. On checking the first test layouts of the points against 

 their own maps, one section was declared to be inaccurate. A transit 

 crew was put at work to check that particular area, and our hastily 

 assembled map was proved accurate within a few inches. 



8 Bingham, Hiram, Mancliu Piccliu : A citadel of the Incas, New Haven, p. 39, 1930. 



