AND NEIGUBOUKING SEAS DURING 1897. 209 



sets with a velocity varying between 8 and 30 miles a day, while to the 

 north of Scotland, over the Wyville-Thomson ridge, it sets towards the 

 Norwegian coast with a velocity of 5 miles a day. But it has to be 

 borne in mind that the orifice of the Dover Straits is very small and 

 the depth exceedingly shallow, scarcely exceeding 20 fathoms along 

 a line drawn from Diiugeness to Boulogne, while the depth of water 

 over the Wyville-Thomson ridge, with which comparison is invited, 

 is 300 fathoms. Moreover, the whole bed of the English Channel 

 scarcely exceeds a depth of 50 fathoms in any part. Friction with the 

 bed of the Channel, combined with the obstacles to further progress 

 presented by the narrowness and shallowness of the Straits of Dover, 

 would appear to be sufficient to prevent the ingress into the English 

 Channel of any serious portion of the general Atlantic drift already 

 retarded by the shallowness of the sea between France and Ireland. 

 That this is actually the case appears from the Admiralty chart of 

 Atlantic surface currents (1875). The bifurcation of the Atlantic drift 

 (the time-honoured Gulf Stream) takes place opposite the entrance 

 to the English Channel, outside a line connecting Ushant with the 

 west of Ireland, thus indicating the serious nature of the obstacle 

 presented by the shallow bed of the Channel ; and in this part of the 

 chart the currents are marked as " variable and uncertain." 



The improbability of any serious current setting through the Channel 

 as an offset from the general Atlantic drift is in agreement with the 

 results of our experiments. The surface currents in the Channel have 

 been shown to be in general agreement with the direction of the local 

 winds from time to time ; and in July, at any rate, there is some direct 

 evidence from our bottles that the water in windless weather is 

 stationary, except for the regular swing imparted to it by the tides. 

 Out of a number of bottles put overboard on the 17th July, during 

 a voyage of the Busy Bee from Falmouth, two, at any rate, were recovered 

 three days later afloat in practically the same spot as that in which 

 they were sent adrift. The weather during this period was almost dead 

 calm, none but the lightest of southerly airs being perceptible. Had 

 any appreciable current, say, of 4 miles a day, been setting up-Channel 

 at the time, the position of the bottles would have been deflected a 

 corresponding amount to the eastwards — 12 miles in the example taken. 

 The velocity of the tidal stream at springs in this region is small, from 

 \ to 2 knot. 



At the same time, as the velocity of the Atlantic drift is admittedly 

 dependent on the force of the winds blowing over that ocean, these 

 considerations do not preclude the possible occurrence of eastward 

 currents in the Channel, independently of local winds, after unusually 

 heavy gales to the west of our islands. We shall, 1 think, be able to 



