ARROYO GRANDE TO TRES ALAMOS-TRES ALAMOS TO GAYIOTE CREEK. 
15 
at the map will convey a better idea of the topography of this point than an elaborately written 
description. The descent of the stream is too great to locate a line through, or near the town 
of San Luis Obispo; it is, therefore, necessary to project the line along the slopes of the 
mountain upon the left bank of the creek, through this second summit, to the small divide 
between Arroyo Grande and Corral de Piedras creek; thence down the right hank of Arroyo 
Grande to near its debouch into the sea. From the summit a descending grade of one hundred 
feet per mile for five miles will he required ; thence an ascending grade of one hundred feet per 
mile for three miles, to the second or serpentine summit, and from this second summit a 
descending grade of one hundred feet per mile to Arroyo Grande; thence along the slopes of 
the right hank of Arroyo Grande to near its debouch, with a descending grade of seventy-two 
feet per mile. 
This entire division is a hold one, and the cost of graduation will be great on account of the 
rocky character of the side slopes, in some instances serpentine, and the deep cuts and fills 
required to keep up an uniform and practicable grade. 
The length of this division is 24.5 miles. 
Maximum grade required 100 feet per mile. 
Probable cost of graduation and superstructure. $2,450,000 
Cost of 3,960 feet of tunnelling, at $125 per foot. 495,000 
Total cost of division (including tunnel)... 2,945,000 
Cost per mile, exclusive of tunnel, $100,000 
Sixth Division. — From the mouth of Arroyo Grande to the Rio de Tres Alamos. — Turning the 
point of the low rolling hills and terraces which lie between the Arroyo Grande and the Santa 
Maria, the line enters and traverses the Guadalupe Largo, an extensive triangular plain, which 
was probably an arm of the sea at a recent geological period, defiles through the low system of 
hills extending from Point Sal southeastward, attains a summit elevation of 631 feet above the 
sea ; thence by a light grade down the slopes of the right hank of the Tres Alamos to the rancho 
of Jesus Maria. The work upon this division across the Largo to the Todos Santos summit is 
remarkably light. From the summit to Jesus Maria the slopes of the hill, are smooth and of 
easy occupation, and of comparatively easy graduation. Bridges of the first class across 
Arroyo Grande, the Santa Maria, and Tres Alamos, will he required. There will probably 
he very little, if any rock cutting upon this portion of the line. 
The length of the division is 32.50 miles. 
Maximum grade required 63.2 feet per mile. 
Probable cost of graduation and superstructure $915,000 
Cost per mile $30,000 
Seventh Division. — From Tres Alamos creek to the mouth of Gaviote creek. —From Tres Ala¬ 
mos two routes present themselves, each of which have their peculiar advantages : the former 
in point of distance and directness, the latter in point of grade and probable cheapness. The 
former route lies over the terraced plain which forms the tongue of land between the Tres 
.Alamos and the Santa Inez river, up the right bank of the latter to the mouth of Sal si Puedes 
creek, two miles above the mission of La Purisima ; thence up the valley of Sal si Puedes to a 
summit elevation of about 100 feet above the sea ; thence down a valley which is tributary to 
the Gaviote Pass at the Rancho del Santa Cruz, and from this point to the mouth of Gaviote 
Pass and creek. The earth work upon this division, in many places, will not he heavy, hut will 
