G4 



HYDROGRAPHY. 



destructive ones which ever happened at this place, in which 18 

 vessels — nearly all of them large and fine ships — were cast on shore, 

 in consequence of their cables having been chafed off — chain cables 

 not being then generally in use, and the bottom much fouled by lost 

 anchors. The risk in this harbor from such causes is much less now, 

 on account of the nearly universal use of the chain cable. 



The northers are indicated by a fall of the barometer, with a day 

 or two of dull, heavy weather, and an increasing swell setting into the 

 Bay, giving timely warning to prepare by securing boats on board and 

 everything else for riding at anchor in a heavy sea. The immediate 

 precursors of it are a lighting up of the clouds and a bright clear sky 

 to the northward and westward, and the looming of the land to the 

 northward off Concon and Quintera, which is not usually visible from 

 the Bay. The worst riding is experienced on the flood tide, the sea 

 setting in very heavy. It is somewhat more moderate with the ebb, 

 which setting to windward and acting as an undertow, prevents so 

 great a strain on the cables; the sea is shorter, but nevertheless 

 vessels ride easier. 



From the experience I have had in this Bay, some precautions in 

 anchoring are deemed necessary, and it would therefore be well to 

 observe the following directions. In the summer season, a single 

 anchor to the southward and eastward is alone required, having a 

 long scope, as the winds are strong from that quarter, and frequently 

 come in heavy gusts off the highlands, rushing down with great force, 

 when vessels are liable to drag off the bank, which is steep. If 

 anchoring to the north of Point San Antonio, you moor with open 

 hawser to seaward ; if to the south of it, in the summer season, it is 

 better to ride at single anchor, steadied by a kedge. In winter, care 

 should be taken not to be in the hawse of other vessels, the harbor 

 regulations being indifferently attended to. Vessels frequently suffer 

 great damage from collision, as any vessel breaking adrift, must neces- 

 sarily come in contact with many others. All should endeavor to 

 moor in a clear berth, so as to be able to ride with a cable on each 

 anchor, say from 90 to 100 fathoms, to insure the certainty of not 

 dragging; the usual depth of water is from 15 to 30 fathoms, mud 

 and sand. 



The anchorage for men-of-war is to the north of Fort San Antonio. 

 It is high water, full and change, at 11 hours 30 minutes, A. m.; 

 and the rise of the tide is 4 feet 9 inches. 



