8 On the Tides of the Western Coast of the United States. 
TABLE No. 4, 
heen ng the values A the ie oe of the diurnal curve (D) deduced ale 9f 
analyzing the curves of obse and ia mapa a theor Lia also the v 
comparison of ie diurnal ‘meqsaiaties measured on 
No. D. M sine 23’ Difference, gmt H. W. 
from curve. 
Feet. Feet. — 
1 2:18 217 04 2°2 
2 201 2:00 -01 2:05 
3 1-79 1-83 04 1°85 
4 1°55 Ol 
5 116 1-20 04 ik 
6 0°81 0-76 — "05 16 
“3 0°25 0-26 1 0°0 
The agreement of the several results compared appears very 
satisfactory. 
The changes in the value of E have been distinctly traced by 3 
Mr. Heaton from the observations; but before presenting the con- 
clusion on this subject, I desire to subject them to the test of fur- 
ther computations, which are now in progress. 
In order not to interfere with the regular work of the hydro- 
graphic party, a separate tidal party has been organized under 
the direction.of Lieutenant Trowbridge of the corps of engineers, 
assistant in the Coast Survey, and supplied with the necessary 
means for a full investigation _ the tides of our Western coast. 
It is proposed to establish three permanent relf-registering tide- a 
gauges, under intelligent supervision, at San Diego, San Francisco, 
and Columbia river entrance, and to connect them by observations 
at suitable intermediate points. here are difficulties to be over- 
come in the character of the coast itself, and of the aborigines 
who still inhabit portions of it, but I expect, Re Bese 
success from the zeal and ability of Lieutenant Trow 
The following tide table results from the sbaherteite ready 
discussed. 
Corrected establishment at Rincon Point: High water, 12 
hours 3 minutes; low water, 17 hours 51 minutes. 
Mean rise and fall of tides, 3 feet 11 inches; of spring tides, 
4 feet 11-8 inches; of neap tides, 2 feet 11 inches 
Mean duration of rise 6 hours 30 0 minutes, including half the 
stand ; fall 5 hours 52 minutes, cexieating half the stand ; stand, 
30 minutes. 
ead er wee er 
High water. | Low water. 
Diurnal inequality - _ Ft. In. Ft. In. 
Average for fore whole month, .. 1 03 2 04 
Greatest 2-11 3 064 
gerne a in Aepssaiion H. M. H. M. 
Average Bs ie Yee 1 02 0 45 
Greatest val 1.2 00 1 06 
| 
Rte Se em alee st 
