AEEOYO GRANDE TO TRES ALAMOS — TRES ALAMOS TO GAVIOTE CREEK. 15 



at tlie 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 bank 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 be 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 bank of Arroyo Grande to near its debouch, with a descending grade of seventy-two 

 feet per mile. 



This entire division is a bold 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 a, 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 637 feet above the 

 sea ; thence by a light grade down the slopes of the right bank 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 be required. There will probably 

 be very little, if any rock cutting upon this portion of the line. 



The length of the division is 32.50 miles. 

 Maximum grade required 03.2 feet per mile. 

 Probable cost of graduation and superstructure |9T5,000 

 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 

 y^lamos 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 700 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 be heavy, but will 



