PHYSICAL FEATURES OF THE IRISH SEA. 



6. TIDES AND CURRENTS. 



In connection with the investigation of the surface life, in discussing- the appearance 

 and disappearance of swarms of certain Copepoda and Medusae, and in considering the 

 possible influence of the movements of food matters upon the migration of fishes, we tried 

 some years ago by means of small "drift bottles" to ascertain the set of the chief 

 currents, tidal or otherwise, such as the movement of surface waters caused by prevalent 

 winds. The Prince of Monaco started a few years before that the system of distributing over 

 the North Atlantic large numbers of small floating copper vessels, with the object of 

 finding out where they drifted to. This plan we have adopted, with slight modifications. 

 In September, 1894, we selected a small, strong, buoyant bottle, measuring 7-5 cm. by 

 i '8 cm., which seemed well suited for the purpose, and which costs only 73. per gross. 

 We afterwards adopted a rather larger size of bottle, 8*5 cm. in length, and substituted stamped 

 and addressed postcards for the slips of paper, as getting rid of various postal difficulties 

 that had occurred. I drew up a notice, as follows, to go in the bottles, and had a large 

 number printed and numbered consecutively : 



NOTICE Anyone who finds this is earnestly requested to write the place, and date 

 when found, in the space on the other side for the purpose, place the paper in an 

 envelope, and post it to PROFESSOR HERDMAN, University College, LIVERPOOL. 



Postage need not be prepaid. 



No [Turn over. 



[OTHER SIDE.] 



Please write distinctly and give full particulars. 



LOCALITY, where found 



Date when found 



Name and address of sender 



A paper was then placed in each bottle, so folded that the number could be readily 

 seen through the glass, the cork was well pressed down, and dipped in melted paraffin. 

 Nearly two thousand of these bottles have, since that date, been dropped into the sea in 

 various parts of our area, a record being kept of the locality and time when each was set 



