This fine thematic map is a copy of the chart constructed for the Smithsonian Institution in 1868 by Charles A. Schottt. Wheat says "that such maps could now be constructed demonstrates the quantity of observational data American scientists had amassed, as well as the effective aid maps could render in the presentation of such data." Legend shows via pattern and color different annual rain falls. From Powell's report that describes the limits of the lands in the arid regions of the West. Lithographed by the firm of Julius Bien.

References: Wheat (TMW) #1290.

Condition: B

Nice example less a little weakness on some folds with splits that have been closed on verso with archival tape. Some roughness in upper margins with several tiny short tears at edge.