82 EXPLORATIONS FROM A. D. 1852 To A. D. 1857. 
lake, and thence to Lost river, near the Natural Bridge. From this place the main party, in 
charge of Lieutenant Abbot, proceeded to Upper Klamath lake by the valley of Lost river, 
while Lieutenant Williamson, with a detached party, followed round the western shore of 
Lower Klamath lake. 
A junction having been effected, the whole party followed Klamath river to Klamath marsh, 
and thence struck across to Des Chutes river. Lieutenant Williamson, with a detached party, 
then explored among the mountains, while Lieutenant Abbot, with the main party, followed 
down the valley. A junction was effected near the Three Sisters, where a depot camp was 
made. Here the main party remained, while Lieutenant Williamson, with a few men, continued 
the exploration of the Cascade range in the vicinity; and Lieutenant Abbot proceeded, with 
another small party, down the valley to Fort Dalles. Finding that the cations, in which the 
tributaries of the Des Chutes river flowed, were so enormous as to render a railroad utterly 
impracticable, he returned to the depot camp, where a final separation took place. 
Lieutenant Williamson, after sending the greater part of the escort to Fort Lane, surveyed a 
pass through the Cascade range near Diamond Peak, and proceeded down the Willamette valley 
to the Columbia river. He then sailed to San Francisco, to prepare for further explorations in 
the Sierra Nevada. Lieutenant Abbot again turned towards the north, and, after exploring 
the vicinity of the Fort Hills, crossed the Cascade range near Mt. Hood by an hitherto unknown 
pass, and then followed down the Willamette valley to the Columbia. Being joined here by 
the party left by Lieutenant Williamson, he proceeded, in aceordance with his instructions, to 
examine the route to Fort Reading lying west of the Cascade range. He followed up the Willam- 
ette valley to the Calapooya mountains, crossed them by an excellent railroad pass, traversed 
the Umpqua valley, and reached Rogue River valley, by the Umpqua cañon, through the 
Umpqua mountains. After crossing Rogue River valley, he passed over the Siskiyou mountains, 
by the wagon route, near the head of Stewart creek, and then travelled through Shasta valley 
to Yreka. The route then led over Little Scott's mountains to Scott's valley, up which he 
passed to its head. He then crossed Scott's mountain to Trinity river, and, after following 
the stream about 25 miles, left it to pass over the Trinity mountains. "The headwaters of Clear 
creek were then struck, and the stream followed nearly to Shasta; thence the route lay through 
the Sacramento valley, for 17 miles, to Fort Reading, where the field work terminated. 
In making the map of this exploration, Lieutenant Abbot embodied various unpublished 
military reconnaissances made in Oregon and northern California, which he duly acknowledges. 
These were: that by Major Alvord, in 1853, from Myrtle creek, in Umpqua valley, to Rogue 
River valley; that by Mr. G. Gibbs, in 1852, from Humboldt bay to the head of Scott's river; 
that of Lieutenant Chandler, in 1856, near the mouth of Rogue river; that of Lieutenant Kautz, 
in 1854, near Coos bay; those of Lieutenant Williamson from Yreka, east of Shasta Butte, to ۱ 
Fort Reading; ; from Yreka to lower Klamath lake; and from Port Orford to E rur and Rogue 
rivers, made e» on military duty in the department in 1851-52. 
UNITED STATES AND MEXICAN BOUNDARY SURVEYS. 
These surveys began in 1849, and continued, with varieus interruptions, till 1856. During 
the establishment of the boundary line agreed upon by the treaty of Guadalupe Hidalgo, four 
different appointments were made of United States commissioner, four of astronomer, and 
two of surveyor. Delays were caused by these changes, by a want of means to properly carry 
on the work, and by differences of opinion as to the proper initial point on the Rio Grande. 
