78 EXPLORATIONS FROM A. D. 1852 To a. D. 1857. 
Mohave valley, and crossed the river in about latitude 34° 50’ north. Leaving the Colorado, 
they took a northwesterly course to Soda lake. They then passed up the valley of the Mojave 
river, and through the Cajon Pass, to the rancho of Coco Mungo, and thence along the foot 
slopes of the Coast range to Los Angelos, where the survey terminated about the 25th of 
March, 1854. 
SURVEY FOR A PACIFIC RAILROAD THROUGH THE PASSES OF THE SIERRA NEVADA AND COAST RANGE, 
LIEUTENANT R. 8. WILLIAMSON, TOPOGRAPHICAL ENGINEERS, 1854. 
The final report of these surveys and reconnaissances forms Volume V of the quarto edition 
of the Pacific Railroad Reports. It is accompanied by a general map on a scale of 1 to 600,000; 
one of certain passes on a scale of 1 to 240,000, and several detailed maps. There are, too, 
sheets of profiles drawn on a horizontal scale of 1 to 120,000, and a vertical scale five times 
greater. The report is also accompanied by geological maps and profiles. "The report and 
general map were also in House Document No. 129, 1st session 33d Congress. 
Lieutenant Williamson was assisted by Lieutenant J. G. Parke, Topographical Engineers; 
Lieutenant G. B. Anderson, 2d dragoons; Dr. A. L. Heerman, physician and naturalist; Mr. 
W. P. Blake, geologist; Mr. Isaac W. Smith, civil engineer; Mr. Charles Preuss, topographer; 
and Mr. Charles Koppel, artist. His escort was commanded by Lieutenant G. Stoneman, lst 
dragoons. Continuous topographical sketches of the routes traversed were taken, and the 
work checked by astronomical observations with the sextant. "Two of the passes were surveyed 
with chain and spirit level. On the map Lieutenant Williamson embodied some of the explo- 
rations of Captain Warner which had not before been published. 3 
The expedition left Benicia on the 10th of July, 1853, and crossed the straits io the town 
of Martinez. Thence, travelling through Livermore's Pass, and turning southeast, the party 
crossed the San Joaquin river at Grayson, and proceeded to Fort Miller. From this place they 
proceeded, via Woodville, to the O-co-ya or Pose creek, seven miles north of Kern river, 
where a depot camp was established for an examination of the passes by small parties. 
Lieutenant Williamson then surveyed the passes at the head of Kern river—one called Chay-o- 
poo-ya-pah or Walker's Pass; the other the Hum-pah-ya-mup Pass. Leaving the latter, he 
proceeded south on the west side of the Sierra Nevada to the Tah-ee-chay-pah Pass, which 
was surveyed, as was also one a little to the south of it, (the one that Captain Frémont 
traversed in 1844, and which he calls ۰۲ Walker's.") Lieutenant Williamson next surveyed 
the Tejon Pass and the Cañada de las Uvas. In the latter of these passes an extensive and 
valuable comparison was made of leveling by the barometer and spirit level, the results of 
which are ably discussed by Lieutenant Abbot, Topographical Engineers, in Volume VI of the 
Pacific Railroad Reports. — 
While Lieutenant Williamson. was E Fere examinations and surveys, | 
Parke was sent with a party to Los Angeles, examining in his route the San Fernando Pass, 
near the Mission of that name. From Los Angeles he proceeded up the San Gabriel and Santa 
Anna valleys, and examined the passes between the San Bernardino and San Gorgonio moun- 
tains, called the San Gorgonio Pass. Thence Lieutenant Parke retraced his steps and joined 
the main party in the Cafiada de las Uvas. 
Lieutenant Williamson, on the 5th of October, passed throogh the. Cafiada de E Uvas, and 
travelling south ward along the base of the mountains, examined the San Francisquito and New 
Passes. On the 19th of October he made a e camp on the Mohave river. From this camp 
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