548 



Captain Spratt on the Undercurrent [June 15, 



the positiveness of such an undercurrent there from the temperature and 

 small difference in the densities, although the results did not show it by 

 the current-drag operation, I am under the necessity of referring to it. He 

 says, paragraph 67, page 182, "We commenced our observations on the 

 morning of October 1st at the point of greatest depth (Station 65). The 

 temperature of the surface at 6 a.m. was only 63°, which was at least 8° 

 lower than the average temperature at that hour within the Mediterranean. 

 The bottom-temperature at 198 fathoms was 54°*5, and the specific gravity 

 of the bottom-water was 1 028*2. The coincidence both in temperature 

 and specific gravity with the bottom-water at Station 64 was thus very 

 close. The place of the ship having been determined by angles taken 

 with the shore, the rate of the surface-movement was tested as on former 

 occasions, and was found to be 1*277 mile per hour, its direction being 

 E. J S. The * current- drag' was then sunk to 150 fathoms, the greatest 

 depth at which it was thought safe to use it ; and the boat from which it 

 was suspended moved E. f N. at the rate of 0*840 mile per hour. This 

 observation indicated a very considerable retardation of the rate of inflow, 

 but gave no evidence of an onflow. It did not, however, negative the in- 

 ference deducible from the temperature, and still more from the specific 

 gravity, of the water beneath, that an outflow takes place in that lowest 

 Stratum which we could not test by the * current-drag.' " 



The remark I feel it necessary to make is, that although the " current- 

 drag" showed no undercurrent here in 150 fathoms in a depth of 198 

 fathoms, but, on the contrary, there appeared to be an E. f N. current at 

 that depth of 0*84, or about f mile per hour, yet against this result Dr. Car- 

 penter insists that f< it did not, however, negative the inference deducible 

 from the temperature, and still more from the specific gravity, of the water 

 beneath, that an outflow takes place in the lowest stratum." Now, ac- 

 cording to the depth, the sounding-drag when down in 150 fathoms was 

 nearly down to the level of the barrier-ridge extending across the Straits 

 there ; and moreover, from the Station being where the depth was so great 

 as 198 fathoms, it was on the west side of the barrier and considerably 

 below it. The temperature in that depth also, being 54°*5, corresponded 

 closely with a temperature obtained by Mr. Jeffreys at Station 37, a little 

 more to the westward, in 190 fathoms, which was there 53°*7, whilst on the 

 Mediterranean side, in 181 fathoms at Station 63, the temperature was 

 54°- 7; so that there was nothing abnormal in these temperatures at about 

 the same depths, on different sides of the barrier-ridge, viz. that of a degree 

 only in one, and in the other on the Atlantic side of about f of a degree 

 lower temperature than that of the Mediterranean side, where it was at 

 its normal temperature of the deeps on that side ; for on the Atlantic 

 side of the barrier the temperature lowers gradually down to its normal 

 depth of about 39g° in the deeper regions, being at Station 35 in 335 

 fathoms 51°-5 at about 30 or 40 miles to the westward of the one at 65, 

 where the "current-drag" operation for testing the current was taken, 



