120 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Scotland and England as far as the Wash, and then east- 

 ward to the Continent ; so that the fish supply of a given 

 area of the territorial waters may be derived not from the 

 offshore spawning areas opposite, but from those situated 

 further north — for example : the inshore waters of the 

 Firth of Forth and St. Andrews Bay derive their main 

 supplies not from the waters lying contiguous to them to 

 the eastward, but from areas further north, such as the 

 spawning grounds in the neighbourhood of the Bell Rock 

 and those off the Forfarshire coast. In the case of our 

 district, the drift is chiefly to the north and north-east 

 (see below) . 



What is already well-known* in regard to the tidal 

 streams or currents in the Irish Sea is that for nearly six 

 hours after low-water at, say, Liverpool, two tidal streams 

 pour into the Irish Sea, the one from the north of Ireland, 

 through the North Channel, and the other from the south- 

 ward, through St. George's Channel. Parts of the two 

 streams meet and neutralise each other to the west of the 

 Isle of Man, causing the large elliptical area, about 20 

 miles in diameter and reaching from off Port Erin to 

 Carlingford, where no tidal streams exist, the level of the 

 water merely rising and falling with the tide. The 

 remaining portions of the two tidal streams pass to the 

 east of the Isle of Man and eventually meet along a line 

 extending from Maughold Head into Morecambe Bay. 

 This line is the " head of the tide." During the ebb the 

 above currents are practically reversed, but in running out 

 the southern current is found to bear more over towards 

 the Irish coast. 



*A11 the accounts I have had access to seem based upon Admiral 

 Beechey's observations published in the Philosophical Trans, for 1848 and 

 1851. Admiral Wharton, F.R.S., the present Hydrographer to the Navy, 

 Iras kindly informed me that Admiral Beechey took his observations by the 

 direct method of anchoring his ship in various places and then observing the 

 direction and force of the tide. 





