Later edition with significant improvements of this extremely rare map of the State of Sonora, colored by Districts. The Royal Geographical Society in its 1885 Proceedings remarked of this map: "This map...is drawn on a larger scale than any yet published, and contains details not to be found in other maps of this same country" (p. 413).
The map was apparently intended for the use of potential investors or land purchasers in Sonora, especially those interested in mines, which along with coal fields, are specifically noted. On the whole, this is a beautifully detailed map of the area that sets forth its physical features, towns, roads, rivers, ranches, and railroads in minute form. The map also shows the Eastern coast of Baja, California, and the far southern part of Arizona. Although this map may seem late, it represented a genuine advance in the mapping of Mexico, which was geographically poorly understood at the time.
Although praising Herbert's map of Sonora as "good," Merrill, concerned primarily with mining interests, decries the lack of accuracy in Mexican maps available at the time. Because of its emphasis on mines, this map, as Merrill intimates, would have been an important one at the time of its publication.