426 APPENDIX. 



flat, extending nearly from point to point, great part of which 

 is dry at low water, and occasions the before-mentioned diffi- 

 culty of landing ; and the north-eastern shore, from Punta 

 San Pablo to the Rio Calavaros beyond San Jose is so flat 

 that lifrht boats only can approach it at high water. In low 

 tides it dries some hundred yards off" shore, and has only one 

 fathom water at an average distance of one mile and a half. 

 The northern side of the great basin beyond San Pablo is of 

 the same nature. 



After passing the fort a ship may work up for the anchor- 

 age without apprehension, attending to the lead and the tides. 

 The only hidden danger is a rock with one fathom on it at 

 low water, spring tides, which lies between Alcatrasses and 

 Yerba Buena islands. It has seven fathoms alongside it : the 

 lead therefore gives no warning. The marks when on it are, 

 the north end of Yerba Buena Island in one with two trees 

 (nearly the last of the straggling ones) south of Palos Colo- 

 rados, a wood of pines situated on the top of the hill, over 

 San Antonio, too conspicuous to be overlooked ; the left hand 

 or S.E. corner of the Presidio just open with the first cape to 

 the westward of it ; Sausalito Point open i point with the 

 north end of Alcatrasses ; and the island of Molate in one 

 with Punta de San Pedro. When lo the eastward of Alca- 

 trasses, and working to the S.E., or indeed to the westward, 

 it is better not to stand toward this rock nearer than to bring 

 the Table-peak in one with the north end of Alcatrasses Island, 

 or to shut in Sausalito Point with the south extreme of it. 

 The position of the rock may generally be known by a ripple; 

 but this is not always the case. 



There are no other directions necessary in working for 

 Yerba Buena Cove, which I recommend as an anchorajre to 

 all vessels intending to remain at San Francisco. 



In the navigation of the harbour much advantage may be 

 derived from a knowledge of the tides. It must be remem- 

 bered that there are two separate extensive branches of water 

 lying nearly at right angles with each other. The ebbs from 

 these unite in the centre of the bay, and occasion ripplings 



