SEA- FISHERIES LABORATORY. 173 



which they were set free. On the same date, and at the same 

 spot (Aberffraw Beach), Bottles No. 6 and No. 61 were found, 

 one having been cast into the sea at Station I and the other 

 at Station VII, thirty miles away. 



The general direction and strength of the tidal streams 

 in the Irish Sea are fairly well known. The ebb-tide is the 

 reverse of the flood, except in the southern area as mentioned 

 above. On the whole, therefore, the distance a floating object 

 travels with the flood will be counterbalanced during the 

 subsequent ebb. Apart from these tidal movements the wind 

 is bound to affect bodies floating near the water surface by 

 causing a drift in the upper layers of water, and also by 

 creating wave motion. 



Considering the prevailing winds during the period of 

 release for the Welsh bottle, it is seen that they tend to cause 

 a decided drift to the southward and eastward, which coincides 

 with the general drift of these bottles. Add to this the fact 

 that the bottles were washed ashore during on-shore winds, 

 and one might be inclined to conclude that they had been 

 strongly influenced by the wind. 



Taking the period between the recovery of the bottles in 

 Wales and the group of nine bottles in Ireland i.e., August 

 26th to Oct. 5th- 18th, the prevailing winds were such as to 

 cause a general drift to the westward and southward. 



The dates of the Welsh and Irish bottles are clearly 

 marked with a difference of a month between them, and the 

 change from prevailing westerly winds to easterly winds 

 coincides with the landing of the Welsh bottles. One might 

 be led to assume, therefore, since one bottle from the extreme 

 Station VII was found in Wales, that all bottles had journeyed 

 towards the Welsh coast, and that those which tailed to land 

 had drifted back towards Ireland. This would mean, 

 however, that the drift on the return journey would be at tin- 

 very least 4-6 miles per day, which seems excessive. 



