Co-tidal lines of the Pacific Coast of the United States. 25 
The cotidal hours calculated from the separate equations are 
for Cape Disappointment 205 00™, Port Orford 19% 44m, agreeing 
precisely with the observed, and for Humboldt 205 09", differing 
ut one minute from the observed. 7 
he observations bearing upon this group are extending north- 
ward, but the difficulties in the way of maintaining the stations 
are such, on a coast inhabited by aborigines, that I do not ven- 
ture to count upon speedy results. Lieut. Trowbridge is using 
his best efforts to establish the necessary stations. 
I precede the discussion of the Middle Group of stations by 
atable giving the results corresponding to several different hy- 
potheses which will in turn be examined. 
fer) oO — i=) to nw is} 
ie = oa Ga RQ oe 
os ) 2 
Smo Babogs mgs = 
BEERS OS pos eS 3. 
ob. 0.0 MEwEe.F mEeE.o = 3 
Moree eee 
. te a : 
o © 
preiscms wer ee A = 
5 Ons a D 2 = 
meeeees Egoos g : 
eEOS 8 BP Bae : ~ 
> = aan D DB yy soe 
SSc BSe SRaFeE 
RATE a UE i = Bee Bee 
QE 2) cs 
8 2 5 § FF Es 9 
ee ee eae 3 
= _ _ —_ oad 6 a} 
- ~ . 
S oS: eee &S to” |Mean Longitude. xy 
pw eo & & o~ 
gs 8 SS P 
ruck tee te a c Mean Latitude. 8: 
oo i) _ (o) o ~ 
a OF OR ee to) 2) bh 48 
~~ J _ pay —_ load 25 b> 
Oe ee eer) oy 
_ ~ _ on on ot ° tt 
a I @ = [74] SBS a ae FS ee = = ey 
no 
o oo ~ i) oo oo F 56 o 
ee se S ps 2 Longitude. gE a = Sos 
pe en Sea ee ee | t Latitude. 2 ¢ & 
: o : rr itu SE 4 
Se ee oe te 8 “I 9 
ea ME eg ee. i) & lope "4 & > 
“a ooo > ae a on as 5 z & 
me = ae LS ee 
- oa. so oo So 22 
Laced B 
" Diff. of cotidal hour Ss s 
_ _ - 0 eo. = |correspond’g toone cd $ 
Ss & & & <2 -T | geog. mile pe . ZI a 
6 to cotidal line. ih ohy 
= ra = |Miles perh’rtidTwave| &. . 
== i erraeoa™ a eee 
ee .x  |San Luis Obispo. as} 5 
at ag my, eo) 
= pai ute _ |Monterey. os BE 
S$  |Santa Cruz. on 3 
j = Ie ; g s 
o oe ro. 'SanFranciseco  & 3 § 
1 f a in | Fe i 
Taking the five sutidigsbetwecn ‘Cape Mendocino and Point 
Conception as one group, we find from the table 
Senizs, Vol. XXI, No, 61.—Jan, 1858. 4 
the angle of the — 
