446 TIDES. 



We found the best anchorage to be a quarter of a 

 mile off the south point of a sandy bay, near the outer 

 end of the island. During the time we lay here for the 

 purpose of obtaining a series of tidal observations,* 



* The result of these observations makes the time of high 

 water at the full and change of the moon 9h. 36rn. when the 

 rise of tlie tide is six feet and three at neaps. The flood stream 

 comes from the eastward ; and both it and the ebb is of 6h. 

 15m. duration at springs; but during neaps the flood runs /h. Om. 

 and the ebb 5h. 30ra. The interval of slack-water never ex- 

 ceeded a quarter of an hour, and the western stream begins 

 Oh. 30m. after low water at springs, and Oh. 50m. after it 

 at neaps ; whilst the eastern begins Oh. 40m. after high water at 

 springs, and Oh. 10m. before it at neaps. The velocity of the 

 stream was from one to tbree knots, the strongest being the ebb, 

 which, at springs and with a strong westerly breeze attains a 

 strength in the middle of the strait of nearly four knots, and 

 causes, when opposed to the wind, a high topping sea, dangerous 

 for small craft. 



Whilst in other respects the tides are the same, the time of high 

 water at Preservation Island, though only at the northern side of 

 the strait, is Ih. 15m. later than at Swan Island. This great 

 difference is caused by the influence of the flood stream out of 

 Franklin Channel and from the northward along the west side of 

 Flinders Island. The flood streams setting to the westward 

 through Banks Strait, and to the south-westward past the north- 

 west end of Flinders, meet about ten miles to the westward of 

 the Chappell Isles, when their united stream curves round by 

 south to west, becoming gradually weaker, and soon after passing 

 the mouth of the Tamar ceasing to be felt at all, leaving in the 

 middle of Bass Strait a large space free from tidal influence as 

 far as the production of progressive motion is concerned, that 

 given to it from the entrances being neutraUzed by their mutual 

 opposition. There is, however, an easterly cuiTent of nearly a knot 

 an hour, in strong westerly winds. The meeting of the tides on 



