A word about New Orleans' drainage problem. The city is the bowl of a dish, of which the levees against river and lake are the rim. There is no natural drainage. The rainfall is nearly five feet a year, concentrated at times, upon the thousand miles of streets, into cloudbursts of four inches an hour and ten inches in a day. In the boyhood of men now in their early thirties it was a regular thing for the city to be flooded after a heavy rain. To meet the situation, New Orleans has constructed the greatest drainage system in the world. There are six pumping stations on the east side of the river, connected with each other by canals, and with a discharge capacity of more than 10,000 cubic feet a second. The seven billion gallons of water that these pumps can move a day would fill a lake one mile square and thirty-five feet deep. Three of the canals empty into Lake Pontchartrain, the fourth, the Florida Walk Canal, into Bayou Bienvenu, which leads into Lake Borgne, an arm of Pontchartrain. Because of this drainage contamination, the lake shore front of New Orleans has been held back in its development. Yet it is an ideal site for a suburb--on a beautiful body of water, and just half a dozen miles from the business district. So the Sewerage and Water Board has been planning ultimately to turn the city's entire drainage into Bayou Bienvenu, a stream with swamps on both sides, running into a lake surrounded by marsh. The Industrial Canal crosses the Florida Walk drainage canal. This made it necessary to build the inverted siphon. A siphon, in the ordinary sense, is a bent tube, one section of which is longer than the other, through which a liquid flows by its own weight over an elevation to a lower level. But siphon here is an engineering term to describe a channel that goes under an obstruction--the canal--and returns the water to its former level. Like the famous rivers that drop into the earth and appear again miles further on, the Florida drainage canal approaches to within a hundred or so feet of the Industrial Canal, then dives forty feet underground, passes beneath the shipway, and comes to the surface on the other side, in front of the pumping station, which lifts it into Bayou Bienvenu. At first it was planned to build a comparatively small siphon, but while the plans were being drawn, New Orleans entered upon its tremendous development. The engineers threw away their blueprints and began over again. They designed one that is capable of handling the entire drainage of the city. And in April, 1920, it was finished--a work of steel and concrete and machinery, costing nearly three-quarters of a million dollars, and with a capacity of 2,000 cubic feet of water a second, 7,200,000 an hour, 172,800,000 a day.