654 
APPENDIX. 
The flood first strikes over from the Lime Rock*', and passing the Island of Alcatrasses, 
where it diverges, one part goes quietly to Santa Clara : the other sweeping over the sunken 
rock, and round the east end of Angel Island, unites Muth a rapid stream through the narrow 
channel formed by Angel Island and the main, and both rush to the northward through the 
Estrecho de San Pablo to restore the equilibrium of the basin beyond, the small rocks of 
Pedro Blanco and the Alcatrasses Island lying in the strength of the stream. 
The mean of eighty observations gave the time of 
high water (full and change) at 
Yerba Buena anchorage .... 
lOh. 
52m. 
The tide at the springs rises 
7ft. 
loin, sometimes 8ft. Sin. 
Neap .... 
1 
10 
Average rate of ebb at spring tide 
2k. 
Of. at neap . Ik. Of. 
Flood 
1 
0 .06 
Duration of flood . .■ . . . 
At Sausalito the mean of seventeen observations gave 
5h., 
25m. 
the time of high water (full and change) 
9 
51 
Rise (full and change) .... 
6ft. 
Oin. 
Neap ...... 
2 
6 
Duration of flood .... 
4h. 
53m. 
On quitting San Francisco, the direction of the wind in the offing should be considered. 
If it blow from the S. W. there would be some difficulty in getting out of the bay to the 
southward of Punta de los Reyes. The residents assert that an easterly wind in the har- 
bour does not extend far beyond the entrance, and that a ship Mmuld, in consequence, be 
becalmed on tlie bar and perhaps exposed to a heavy swell, or she might be swept back 
again, and be obliged to anchor in an exposed situation. Northerly winds appear to be most 
generally approved, as they are more steady and of longer duration than any others : they 
may, indeed, be said to be the trade-wind on the coast. With them it is advisable to keep 
the north shore on board, as the strength of the ebb takes that side, and as on the opposite 
shore, near the One Mile Rock, the tide sets rather upon the land. In case of necessity, a ship 
can anchor to the eastward of the One Mile Rock ; but to the S. W. of the rock the ground 
is very uneven. The wind generally fails in the entrance, or takes a direction in or out. From 
the fairway steer S. W. W. and you will carry seven fathoms over the bar, i ebb, spring 
tide. This I judge to be a good course in and out with a fair wind. I would avoid, by every 
endeavour, the chance of falling into the sandy bay to the southward of Lobos Point, and 
also closing with the shore to the N. W. of the Punta Boneta. 
* See the Chart. 
