NARRATIVE OF THE CRUISE. 



275 



the Cape, but the alteration was by no means gradual, for on one day it varied more than 

 5°; and as these variations did not take place on those days which were bright and sunny, 

 it was concluded that they were due to the Agulhas Current. 



On the 28th, at 7 a.m., a series of temperatures at intervals of 10 fathoms 

 down to 100 fathoms was taken. At noon on the same day a second series was taken 

 1 5 nautical miles to the southwest of the Cape of Good Hope, and it was found that 

 in the interval the ship had passed into the loop of the Agulhas Current, which curls 

 round the Cape close to the land. The contrast between the two series is remarkable. 



A Series of Temperature Observations taken just before, and one taken immediately 

 after, entering the Agidhas Current, October 28th, 1873. 



The temperature of the air likewise rose perceptibly, the thermometer in the shade 

 indicating at noon 5 8° "8, nearly three degrees above the average of the same hour during 

 the previous week. 



The temperature of the bottom water varied from 35°'2 to 34°'2, the lowest result 

 being obtained at 2325 fathoms 130 miles west of the Cape. 



The serial temperatures showed that the isotherm of 40° occupied a mean depth of 370 

 fathoms, varying from 320 to 400 fathoms, the maximum depth being in the centre of the 

 section, and the minimum at the Cape. The isotherms of 45° and 50° indicated this 

 peculiarity in a still more marked degree, for they may be said to be bow-shaped. The 

 isotherm of 55° was irregular (see Diagram 6). 



