100 



Capt. G. S. Nares on the 



[Jan. 18, 



At 2 hours after low water, the density of the bottom-water in 1 70 fathoms 

 having been ascertained, a boat was anchored midway between Tangier and 

 Cape Plata. At 3 hours after low water the surface-current was found to be 

 running to the westward one knot an hour by log- line. A current-drag was 

 then lowered 125 fathoms. By mast-head angles from the boat at anchor 

 it drifted in ten minutes N. 87° W. 450 yards =1*35 mile an hour. The 

 drag pulling its buoy through the surface-water to the westward indicated 

 that the bottom-water was really moving at an estimated rate of 1*5 mile 

 an hour. At 4 and 5 hours after low water, shore positions showed that 

 the surface-water was running S.S.W. 0*4 mile an hour; and at 5^ hours 

 it was stationary. 



The observations on this day, although not so continuous or complete as 

 those taken subsequently, proved that the bottom-water was affected by 

 tidal influence, running to the westward as the water was rising, and to the 

 eastward as the water fell. 



August 23rd. — One hour and a half after high water, the weather being 

 calm, with smooth sea, a buoy was anchored in 125 fathoms, with 25 

 fathoms of light chain and 150 fathoms of No. 2 sounding-line, on the north 

 part of the shallow ridge stretching across the Strait between Capes Spartcl 

 and Trafalgar. 



The surface-current, and probably the bottom-water also, was running 

 so strongly to the eastward that the buoy sank from the pressure of the 

 water against it and the line. As it did not show itself again at slack 

 water, it probably collapsed from pressure. Two buoys were then anchored 

 in the same place with a similar line and chain. The lower buoy sank 

 below the surface, leaving the second one floating with one foot of the top 

 above water, indicating a strain of nearly 200 lbs. exerted by the pressure 

 of the current on the line and buoys. At 2| hours after high water the 

 surface-current was running east 1*25 mile an hour by log-line. At a 

 depth of 25 fathoms the direction and speed of the under-current were the 

 same. At 3| hours after high water, the drag was lowered to 100 fathoms, 

 when a perceptible retardation of the under-current was observed, the 

 surface-water setting to the east past the boat at an estimated rate of | knot 

 an hour. 



The drag was then lowered to 119 fathoms, being 6 fathoms from the 

 bottom, and attached to a buoy ; and on being observed half an hour later, 

 or about 5 hours after high water, it was found by mast-head angles to 

 have drifted E.N.E. 0*09 mile= 0*18 mile per hour. In the mean time 

 the second buoy at anchor floated on its bilge, showing the surface-tide to 

 have slackened and the strain to have lessened to about 110 lbs., estimated 

 as being equal to J a knot. Soon after the top of the underneath buoy 

 floated one foot out of water, indicating a further decrease of tide. 



At low water the bottom current-drag had drifted during the last hour 

 0'1 mile N.W. by N. The surface-current was running past the buoy to 

 the eastward, and was therefore exercising some influence on the current- 



