Page:Popular Science Monthly Volume 66.djvu/288

284 eliminate mosquito breeding places; but that sort of reclamation is expensive and the total bill would be so great as to make it impossible to obtain consideration from any legislature. For the purpose of preventing mosquito development, reclamation is not necessary; it needs only such works as will enable all surface water to drain off completely in less than a week, or as will fill all depressions to a general level, whatever that general level may be.

The average marsh bottom is a tough clayey mud of variable depth, overlaid by a turf from six inches to a foot or more in thickness. This material is like a huge sponge from which the water will run out if it gets a chance, and which will absorb an enormous quantity of surface water. Its texture is also such that it will maintain even a narrow ditch perfectly and, if it is deep enough—two feet or more—no growth will start from the bottom. For slow drainage a ditch six inches wide, that will affect from thirty to fifty feet on each side can be cut by machine, and will dry off even the heaviest precipitation of rain in twenty-four hours. If a spring tide soaks the marsh the drainage is slower; but the surface will be free of shallow pools within forty-eight hours.

Lest it should be considered that this is all a statement of belief merely it should be said that in 1903 several bad areas near Newark and Elizabeth were experimentally ditched. When the work was begun the marshes were soft, full of holes, water-logged and hip boots were a necessity. The crop of salt hay could not be gathered until winter and lawn shoes for horses where they could be used at all, were a necessity. Throughout 1904 it was possible to walk over the drained area at all times, dry-shod except after heavy rains, and then twelve hours were enough to dispose of every pool or puddle. The crop of hay was heavier than for many years past, much of it was cut by machine and horses could be taken everywhere. Practically no mosquitoes developed on these areas.

The most convincing work however was. done on the Shrewsbury River, extending from Seabright to North Long Branch and including nearly all the marsh area on both Monmouth Beach and Rumson neck sides of the stream. The territory had been roughly surveyed during the season of 1903 under the direction of local associations, and during the winter, at the request of these associations, one of the field agents and afterward an engineer was sent down to lay out a general drainage scheme. Before even the frost was out of the ground work was begun, and very soon afterward, in early March, wrigglers made their appearance in every pool and millions of potential mosquitoes were on the marsh. But the weather remained cold, larval growth was slow and the work was systematically pushed so as to reach the worst places first, the sods removed from the ditches being