Page:Popular Science Monthly Volume 20.djvu/238

226 and adapted to our extensive territory, which have been developed in this country within the last quarter of a century, through the successive mediums of the itineraries of exploring parties, the various boundary surveys, Whitney's California Survey, Clarence King's Fortieth Parallel Survey, Hayden's and Powell's geological surveys, and the geographical surveys and other frontier operations of the Engineer Bureau. The methods in question combine the rapid reconnaissance, the mountain sketch, and the barometrical height upon a precise geodetic basis, incorporating all reliable information attainable from other sources, especially the land-surveys, which give certain points in roads and streams, and the perimeters of valleys and areas of water. In the end we have a map of which the error is, in general, inappreciable, and the cost in time and money is comparatively insignificant. Yet so faithfully may the features of a country be portrayed in this way, that the map of Lake Tahoe, the subject of this note, is sufficient to guide the engineer in his projects, the geologist in his studies, the tourist on his travels, the soldier on his march, and the emigrant in his search for a home.

So much for its usefulness, which is the first and principal mission of a map. As a work of art, graphically delineating the configuration of a district of surpassing beauty and variety of scenery, it will, perhaps, possess greater interest to the ordinary observer than any scientific value of accuracy and completeness could give it. If a person were called upon to construct an ideal map which should group together specimens of all types of topographical form and the conventional signs known to the draughtsman, he could hardly derive from his imagination a chart more comprehensive than this. There is certainly nowhere else in our country an area of equal extent so diversified and broken. Extending from latitude 38° 45' to 39° 32', and from longitude 119° 33' to 120° 22', it reaches from the desert inland basin of Nevada to the timbered and grassy mountain-spurs—embraced by the multitudinous forks of the American River—with which the Sierra Nevada range descends into the Sacramento Valley of California.

Lake Tahoe is a sheet of water some ten by twenty miles in extent, situated high up in the heart of the Sierras. The mountain-range divides to receive the lake, forming a cup-like space in which its clear waters are gathered. On the map the lake is given the place of honor, in the center. Its surface, being six thousand two hundred feet above sea-level, is not far below the rim of mountains which inclose it, but which, however, slope to great depths in the Carson Valley on the east and toward the Pacific coast on the west. The range in altitude, from the lowest to the highest point on the map, is more than seven thousand feet, there being three mountains—Freel's Peak, Pyramid Peak, and Mount Rose—standing at three corners of the lake, which are upward of ten thousand feet in height. Thus the subject, taken as a whole, is an admirable one for cartographical expression and