532 NOTES ON THE PHYSICAL CONDITIONS EXISTING 



on the one hand, from Beer towards Portland, the stream gradually 

 increases from almost nothing in strength to over five knots per hour. 

 As we pass backward along shore from Beer towards the Start we pass 

 through Teigiimouth Bay, where the current is scarcely felt, Torbay, 

 where it is uncertain and variable in direction, until we come to Berry 

 Head and Mudstone Ledge, where the current is setting to the westward. 



On the shore of the western half of the area there is, therefore, a 

 backward eddy during the latter half of the flood-tide. Wheeler, in 

 describing this peculiar phenomenon for Start Bay, imagined that the 

 flood-tide was deflected from the cliffs forming the north-eastern bound- 

 ary of Start Bay, and thus entered the bay from its north-eastern 

 aspect. Apart from the inherent improbability of such a tiling, this 

 explanation leaves out of count the presence of the backward eddy 

 over Mudstone Ledge close to Berry Head. 



Along Slapton Sands, in Start Bay, the current sets towards Start 

 Point the last half of the flood and the whole of the ebb, i.e. for nine 

 hours out of the twelve. Along Chesil Beach, at the other corner, the 

 current sets towards Portland also for nine hours out of twelve, but 

 there it is during the last part of the ebb and the whole of the flood. 



The tidal phenomena close to Portland repeat what has already been 

 described as occurring off Beer Head. Two miles west of Portland 

 Bill the direction of the currents turns round a complete circle, so that 

 after three hours of ebb-tide the current sets northerly into the bay, 

 and to counterbalance this inset there is an outward eddy along Chesil 

 Beach. This northerly set of the current is probably due to the fact 

 that the flood is already making to the west of Start Point. To the 

 west of Portland Bill, therefore, there is a circular motion of the waters 

 during the last part of the ebb. 



The comparison of the currents at the two extreme ends of the area 

 may be carried still farther. At the eastern end the stream passing 

 round Portland 33111 meets with an opposing ebb and eddy from beyond, 

 and thus helps to form the "race," which passes on to and over the great 

 sandbank known as the Shambles. At the western extremity the eddy 

 issuing from Start Bay also forms a race with the opposing flood-tide 

 coming from the west, and this race extends obliquely from the shore 

 for nearly a mile in a south-westerly direction. The outgoing eddy, 

 however, is weak in comparison with that at Portland, so that the race 

 is not a strong one, and the sandbank, instead of being in the direct line 

 of the race, lies farther to the north-east on the line of the flood-tide. 



The conditions, so far described, obtain generally throughout the year, 

 but are more particularly marked during spring-tides. During neaps, 

 the water is almost stagnant over the whole western area, and the cur- 

 rents alonji shore are feeble and uncertain in direction. In Teisnmouth 



