Jan. 19, 1877.] 501 [Kane. 



Coahuila, 

 By Thomas L. Kane. 



{Bead before the American Philosophical Society, January 19, 1877.) 



I. GEOGRAPHICAL. 



I have recently returned from a three months' excursion into Northern 

 Mexico. I went by rail to near San Antonio, Texas ; from there took my 

 own and government servants' wagons and mule teams. I was in no 

 hurry, carried a party of intelligent friends with me as observers, and en- 

 joyed advantages for seeing the country and its people which do not com- 

 monly fall to the lot of travelers. 



I spent most of my time in Coahuila and Nuevo Leon. After visiting 

 the country north-west of Piedras Negras, I looked up the different passes 

 of the Sierra Madre which appeared inviting for railroad purposes from 

 below Santa Rosa to La Rinconada. Finding Saltillo closely invested by 

 Trevino, I crossed from the Saltillo road to Monterey, and thence returned 

 to San Antonio via Mier and Laredo. I expect to have time soon to pre- 

 pare a geographical paper and maps for the Transactions of the Society. I 

 shall ask their patience this evening for the communication of a few facts 

 not undeserving their notice. 



1 have drawn upon the blackboard, upon an enlarged scale, the leading 

 features of Colton's latest Map of Mexico. I would ask your attention first 

 to the contrast presented by the Rio Bravo to the other rivers of Southern 

 Texas and Mexico. These are all greatly less conspicuous. They are 

 seen to flow but short distances from their sources to the Gulf of Mexico. 

 The Bravo or Grande del Norte, on the other hand, cuts a more important 

 figure on the map, outdoing, apparently, the others put together. It is of 

 much greater length and volume, and the reason is obvious. 



By the contour lines, where you observe my effort to make hatchings 

 with the yellow chalk, I indicate in a general way the course of the high 

 land which is customarily spoken of as the East Branch of the Sierra 

 Madre. From San Luis Potosi, here, (A) I have drawn the so-called 

 Sierra as extending to the edge of the plain watered by the Rio Grande 

 (B). It sinks as it proceeds north, until here, you see, only one mass of 

 mountain north of Santa Rosa, I have represented it as entirely disap- 

 pearing. 



We have here our explanation of the greatness of the only Mexican great 

 river, the Rio Grande. The great river, you remark, rises in the interior, 

 more than half way across the continent, and it flows all this way as many 

 as 1800 miles, to the Gulf ; because no mountain obstacle is offered to its 

 progress. It finds what might be regarded as a vast Pass where the ' ' Sierra' ' 

 has gone under. It is true (this is a parenthesis for our Secretary) that 

 here (a) it is deflected, and, obedient to local geological orders, turns nearly 

 at right angles, and works along at disadvantage for some distance, until 

 it hits this seeming continuation of the valley of the Pecos (b). But it is 



