National Geographic : 1965 May
Nile-borne Yankee takes a last look at the massive cliff-cut temples of Ramesses II and SOCIETY MAPS THE RIVER OF NCIENT WISE MEN talked of it with wonder: For one moment each year high noon on June 21, the summer solstice-sunlight shone upon the water of a deep well in Syene on the banks of the Nile. Some 500 miles north in Alexandria, Era tosthenes, a philosopher of the 3d century B.C., heard of the phenomenon. So he stood a pole upright in Alexandria and at noon on June 21 measured the angle of its shadow, 71/5 degrees-or 1/50 of a circle. He knew that, according to Euclid, this equaled the angular distance between Syene and Alexandria; to compute the earth's circumference, he multi plied by 50 the accepted linear distance be tween the two cities. Though the philosopher's measurements were imprecise, his concept was sound. The world, Eratosthenes concluded, was approxi mately 28,000 miles around-an error of only about 12 percent. Thus globular geography was born beside the Nile. 634 The well has vanished, and ancient Syene now bears another name: Aswan. With its High Dam, the Nileside city again figures in the story of man's progress; both its names appear on the special 11-color supplement map, Nile Valley, Land of the Pharaohs,* distributed to Society members with this issue of their magazine. A Chart of Time and the River The two-panel archeological map, a year and a half in the making, shows 1,850 miles of the world's longest (4,145 miles) river. Notes chronicle Egypt's course through 52 centuries. On the back of the map-together with an index-history ranges from the first known men in the Nile Valley down to the Egyptians of our own time. Society cartographer George *Additional copies of the Nile Valley-and all other Atlas Series Maps published as supplements to NATION AL GEOGRAPHIC-may be ordered for 50 cents each, postage prepaid, by writing to Dept. 247, National Geographic Society, Washington, D. C . 20036.