Page:The National geographic magazine, volume 1.djvu/417

 the impenetrable veil of the tropical thicket, feast upon views of the distant mountains, the crisp waves of the Lake, and the blue expanse of the Pacific. During the day he meets black-eyed and brown-limbed señoritas, instead of wild hogs and turkeys, and at night as he turns in, he hears, not the scream of tigers, but the songs of the lavandera's ecru daughters floating across the stream which supplies their wash-tubs and his camp.

The first grand natural feature which arrests attention in the most cursory examination of the map of Nicaragua is the Great Lake. This lake with an area of some three thousand square miles and a water-shed of about eight thousand square miles, is unique in the large proportion of its own area to that of its water- shed. A result of this large proportion of water surface to drainage area, at once evident, is the very gradual changes of level of the lake and their confinement within very narrow limits. The difference between the level of the lake at the close of an abnormally dry season and its level at the close of an abnormally wet season is not more than ten feet, and the usual annual fluctuation is about five feet.

The next features that arrest attention are, first, the very narrow ribbon of land intervening between the western shore of the Lake and the Pacific, and second, the entire absence of lateral tributaries of any size to the upper half of the San Juan River. The river is in fact, as it was originally most aptly named, simply the "Desaguadero" or drain of the Lake.

The length of this river is one hundred and twenty miles, from the Lake to the Caribbean Sea, and its total fall from one hundred to one hundred and ten feet. Nature has separated the river into two nearly equal divisions, presenting distinct and opposite characteristics.

From Lake Nicaragua to the mouth of the Rio San Carlos, a distance of sixty-one miles, in which occur several rapids, the total descent is fifty feet, quite irregularly distributed however. The surface slopes of the river vary from as much as 83.38 inches per mile for a short distance at Castillo rapids, to only .90 inch per mile through the Agua Muerte, the dead water below the Machuca rapids.

The average width of the river through this upper section is seven hundred feet, the minimum four hundred and twenty. In some parts of the Agua Muerte the depth varies from fifty to seventy-five feet.