DESCRIPTION OF THE COUNTRY. 25 
limits, where it will require at least sixty feet grade, and from thirty-five to forty feet cutting, to 
attain the summit. From this summit, a little south of Las Lagunas, to the main summit of 
the Rocky mountains, at the San Pedro mountain, the line traverses a rolling country, descend- 
ing at an average rate per mile of about rient cinta feet to the lowest point of this basin, which 
drains, it is supposed, into or towards Las Salinas. From this point the San Pedro Bag can 
be approached with a grade of about thirty-five feet per mile. 
San Antonio Pass. 
“This pass divides the waters which flow into the Rio Tuerto from those that flow into, or 
towards, Las Salinas. About nine miles farther is another pass or summit, which divides the 
waters of the Tuerto from those of the Rio San Antonio, in the Cafion de Carnuel, with a forty- 
feet cut at the San Pedro summit, and a descending grade of about eight feet per mile for seven 
miles. We pass the second summit with only about forty feet cutting, and thence descend at 
the rate of about eighty-two feet per mile for thirteen miles; thence down the sloping mesa to 
the Rio Grande, opposite Isleta, at a rate of about from twelve to fifteen feet per mile. At 
Isleta the Rio Grande contracts through a comparatively narrow gorge, presenting a most favor- 
able point for crossing. Three spans of from one hundred and fifty to two hundred feet will 
effect this object, there being a bluff on both sides favorable for landing without embankments.’ 
4n 
