22 Co-tidal lines of the Pacific Coast of the United States. 
Art. [V.—Approrimate Co-tidal lines of the Pacifie Coast of the 
United States, from observations in the United States Coust 
Survey; by A. D. Bacue, Superintendent. Communicated 
by authority of the Treasury Department. 
THe wesiern coast of the United States, between San Diego, 
California, and Columbia river, extending through 13° 35’ of lat- 
itude, an nd 6° 43’ of longitude, is divided into three reaches, 
(see plate, ) the first from San Diego to Point Conception, the sec- 
ond from this point to Cape Mendocino, and the third from that — 
Cape to Cape Disappointment at the mouth of the Columbia. 
The first reach, about 220 miles in extent, is curved, the general 
trend being about N. 56° W. The second, about 430 miles in 
extent, is in general straight, with moderate indentations only, — 
and its trend is about N. 27° W. ‘The third, 370 miles in extent, 
is also nearly straight, trending nearly N. 5° E. : 
The soundings on the coast generally, except in the harbors, - 
have been for the purpose of general reconnoissance, and are not 
detailed enough to show the configuration of the bottom. 
Tidal Observations. 
Tidal stations for long series of observations have been estab- 
lished at San Diego, San Francisco, and Astoria, (Columbia river, ) 
and between these, temporary stations at the points and for the 
periods stated in the annexed general table. Saxton’s self-regis- 
tering gauge has been employed at the permanent stations gene- 
rally and at some of the ek stations also, 
The observations are under the direction of Lieut. W. P. 
Trowbridge, U. S. Corps of Engineers, and Assistant in the 
Coast Survey. They were commenced in 1853, and are still in 
progress. ‘he very intelligent and careful supervision of this 
officer is a guaranty for the character of the observations. 
observers too were especially selected by him for ei faithfal- 
ness ane Wn igence 
Th mber of results collected i is such as to warrant an a 
ries embraced in this dns, the name of the observer, and 
the kind of gauge aun 
