§2 ENGINEERING REPORTS. 
it may be said you are still on the Pacific plains, and have the 
main and only difficulty to overcome, viz., to find a passage 
through the mountains north of, and parallel to, the Masahua 
range. 
I have deemed it proper to say this much in regard to the 
lower portions of the Masahua mountains, because it has been 
thought, that once through this range, there would be no trouble 
in finding a passage to the Chivela plains ; and to show that 
any gap in the Masahua has little, if any thing, to do with get- 
ting a railroad line through the mountains. 
As to the low depression formed by Arroyo de Juan, imme- 
diately at the east base of Cerro Prieto, I am of the opinion, 
from the appearance of the formidable hills between this chain 
of mountains and Chivela, that there are almost insurmountable 
difficulties to be overcome, unless it should be thought advisable 
to cut a tunnel from one to two miles in length, near the source 
of Arroyo de Juan, through to the plains of Chivela. 
The same may also be said of the openings through the 
mountains at the west end of Cerro Masahuita, formed by 
Arroyo de Molino. 
The four Passes of East and West Piedra Parada, Tarifa, and 
Convento, can be reached, with a railroad line by coming up the 
valley of the Tarifa River, and so on to the plains of that name. 
The Chivela and Tarifa plains are distinctly separated by a long 
dividing ridge, whose principal point is Cerro Timbon. 
