Note 21 — Regular Meeting, March 5th, 1866.

The best map of Northern Mexico is that of M. de Fleury, published in San Francisco, in 1864; but this makes little pretense to a delineation of the topography; the courses of the principal streams and the position of the larger mining towns are often very far from being correct, as must be expected on a map constructed without a basis of instrumental surveys. J. D. W.