306 OBSERVATIONS ON THE CURRENTS. 



such times, should keep, at the highest, 48^ 45', because in 49^ 30' the 

 whole effect of the current may be experienced in the worst situation. But 

 from the Current in 48° 45', a Southerly wind will set the ship into the 

 Channel. Coming from the Atlantic, it would be still better to make 

 Ushant. 



"3rd. That ships, bound to the Westward from the Channel, with a 

 South- Westerly wind, so that it may appear indifferent which tack they 

 go on, should prefer the 2>ort tack, as they will then have the benefit of the 

 Current." 



(256.) In a Supplementary Paper on the effects of Westerly Winds in 

 raising the level of the English Channel, dated 22nd June, 1809, Major 

 Rennell stated ; — 



" In the observations on a Current that often prevails to the Westward 

 of Scilly, which I had the honour to lay before the Eoyal Society many 

 years ago, I slightly mentioned, as connected with the same subject, the 

 effects of strong Westerly winds, in raising the level of the English Channel, 

 and the escape of the superincumbent waters, through the Strait of Dover, 

 into the then lower level of the North Sea. 



" The fact of the high level of the Channel, during strong winds between 

 the West and S.W., cannot be doubted; because the increased height of 

 the tides in the Southern ports, at such times, is obvious to every discern- 

 ing eye. Indeed, the form of the upper part of the Channel, in particular, 

 is such as to receive and retain, for a time, the principal part of the water 

 forced in, as may be seen by the chart ; and as a part of this water is con- 

 tinually escaping by the Strait of Dover, it will produce a Current, which 

 must greatly disturb the reckonings of such ships as navigate the Strait, 

 when thick weather prevents the land, or the lights of the Forelands and 

 the Goodwin, from being seen. 



" There is another circumstance to be taken into the account, which is 

 that the shore of Boulogne, presenting a direct obstacle to the water im- 

 pelled by the Westerly winds, will occasion a higher level of the sea there 

 than elsewhere ; and, of course, a stronger line of the Current toward the 

 Goodwin. 



" It must, therefore, be inferred, that a ship passing the Strait of Dover, 

 at the back of the Goodwin Sands, during the prevalence of strong West 

 or S. W. winds, will be carried many miles to the Northward of her reckon- 

 ing ; and, if compelled to depend on it, may be subject to great hazard 

 from the Goodwins. 



" It will be understood, of course, that although the stream of Current 

 alone has been considered here (in order to simplify the subject), yet that, 

 in the application of these remarks, the regular Tides must also be taken 

 into the account. But, from my ignorance of their detail, I can say no more 

 than that I conceive the great body of the Tide from the Channel must be 

 subject to much the same laws as the Current itself. The opposite Tide 

 will, doubtless, occasion various inflections of the Current, as it blends 

 itself with it — or may absolutely suspend it; and the subject can never be 

 perfectly understood without a particular attention to the velocity and direc- 

 tion of the Tides in moderate weather, to serve as a good groundwork." 



(257.) After the publication of the first paper on the Currents of the 



