Books: Potamography

THE NILE : THE LIFE STORY OF A RIVER —Emil Ludwig—Viking ($5).

Emil Ludwig has written 13 biographies. Each of them, winding somehow safe to the last page, made him think of a river. And once a river made him think of the life of man. Then (1924) and there (the great dam at Aswan on the Nile) he decided to write a potamography —the life story of a river. The big job took him a long time, for the Nile covers a lot of ground, has been flowing a long time, has affected many races of men. Last week Potamographer Ludwig's book was ready at last. First readers found it appropriately like its subject: broken by cataracts, meandering, sometimes almost lost in swamps, often muddy, often turbulent, but on the whole predictable and laden with useful silt.

In the Nile's career Ludwig sees a comforting parable for careerist man. For half its 4,000-mile course the river flows through the desert, receiving "neither tributaries nor rain, yet it does not dry up; indeed, close to its end, it creates the most fertile of all lands." Ludwig calls the Nile the world's greatest river, and his 619 pages of testimony bear him out. "Its basin contains the biggest lake of the eastern hemisphere, the highest mountains, the biggest city of its continent." It owns "the richest bird life of the northern hemisphere, nearly every animal species known to Paradise," vegetation ranging from the Alpine to the tropical, the gamut of geography, hundreds of races. From prehistoric times to the present, its upper reaches have given men gold. (Estimated annual revenue in Ethiopia: $400,000.) And its recorded history is the world's oldest: 6,000 years. The Nile has two sources, both undiscovered until recent times. Source of the White Nile, Lake Victoria Nyanza, was found by Speke (1862); source of the Blue Nile, near Lake Tana in Ethiopia, by Samuel Baker (1864). At Khartoum the two branches join, go on to form in the desert the oasis of Egypt.

The annual Nile flood, on which Egypt's fertility depends, comes in summer, when rivers normally shrink. From June to September the Nile rises 13 to 14 ells (1 ell = 7/10 yd.) in Upper Egypt, 7 to 8 ells in the Delta. Value of the flood is twofold: water for irrigation, silt for crops. Fertilizing value of the Nile's silt has been assessed at $7.50 an acre. Seventy percent of Egypt's cultivated land yields double or treble harvests; in some places there are seven harvests in 15 months. Could Mussolini starve Egypt by damming Lake Tana, diverting the waters of the Blue Nile from Egypt? No, says Ludwig; only 3% of Egypt's water comes from Lake Tana, none of its precious silt. From immemorial time the Nile's floods have been Egypt's prime worry. Too little water means famine; too much, catastrophe. Since Egypt has been under England's benevolent paw, the Nile has been studied, shackled as never before. British hydrographical research costs $500,000 a year; the great dam at Aswan, built to regulate the Nile's flow, took three years to build, had to be thrice heightened, cost $21,000,000.