National Geographic : 1938 Dec
Photograph by Egyptian Army Air Force MORE THAN 5,000 YEARS AGO THESE PYRAMIDS OF GIZA WERE BUILT TO BE THE TOMBS OF KINGS AND QUEENS Compared with them, near-by Cairo is a new city. Such overflows in this part of the delta now are preventedbybarrage and canal control works. The new irrigation system also enables farmers to reap three crops a year, instead of only one, as when they had to dependon the Nile's annual rise. Inthe Great Pyramid at the right a ventilating shaft was so placed that when Sirius, the Dog Star, crossed the meridian-marking the beginning ofthe Egyptian year and the flood-time ofthe Nile-its rays would shine straight down into the royal chamber of Cheops. The Sphinx is seen between the two largerpyramids, slightly inthe foreground.