fea 
ray 
Co-tidal lines of the Atlantic Coast of the United States. 
Comparison of daily inequality with moon’s declination. 
San Diego. Astoria. 
h Ae ert We m sin 20’. | Difference. Nor ne a m sin 26’. | Difference. 
feet. feet. Feet. feet. 
1 2°03 1:90 13 1:94 1:80 
2 1:93 1:83 10 175 ETS 03 
3 155 1°70 —15 1-78 1°60 
| 4 1:26 1:48 — 22 1:32 1:40 — 08 
5 84 114 —°30 98 1:10 rept 
6 63 “15 cage & “49 ae 
kell 69 “28 41 “24 28 — 04 
The observations of which these form a part are still in pro- 
gress, under the direction of Lientenant Trowbridge, whose assi- 
duity and intelligence have already been rewarded by the success 
I had ventured to anticipate in my former reference to the tides 
of the western coast. : 
Art. II].—Preliminary determinations of Co-tidal lines on the 
Ailantic Coast of the United States, from the Coast Survey 
Tidal Observations ; by A. D. Bacue, Superintendent.* 
(Communicated to the American Association for the | ele ea of Science, by 
authority of the Treasury Department.) 
In the progress of the hydrography of the es coast of the 
ments of the ports. With them I have connected observations of 
a more permanent character, intended to furnish the data for ascer- 
taining the laws of the tides in important localities, and others 
for tracing the progress of the tide-wave along the coast generally, 
and in special cases in sounds, Fhe and rivers. These observa- 
are necessary for the purpose. My attention has been called, also, 
by the request of a valued friend, the Master of Trinity College, 
Cambridge, to some attempt of this sort, and his labors in con- 
nection with this subject on our own coast have entitled his re- 
quest to the most respectful consideration. 
pe Report of the Sw tendent of t e progress of the 
ese drag the cen ihe p. 147. ickeain ite 3 ie = 
