NARRATIVE OF THE CRUISE. 419 



higher maximum temperature, showing distinctly that they had entered or passed through 

 a warmer stratum of water than had been indicated between the surface and a depth 

 of 200 fathoms. The minimum indices all registered 29°, agreeing exactly with what 

 had been found at lesser depths. At 200 fathoms the thermometers both showed a 

 slight, but only a very slight, rise in the maximum index ; but as they both agreed 

 exactly, it is probable that at this depth the warm underlying strata commenced. It 

 is impossible that the thermometers could have been affected in their momentary passage 

 through the air (which was at a temperature of 33°) from the sounding bridge to the 

 surface of the water, as the utmost care was taken to keep the outer case filled with the 

 cooling mixture until the instrument was immersed, and on recovering each thermometer 

 it was detached and read off before the mercury had sufficient time to attain a higher 

 temperature than that of the surface water (29°'5), besides, if they were affected 

 by the air, all the instruments would have registered higher on the maximum side, 

 whereas only those lowered to depths exceeding 200 fathoms did so. The temperature 

 of the bottom water ranged between 33° and 28°'8, these being the temperatures regis- 

 tered by the maximum and minimum indices of the instrument sent to 1675 fathoms. 



On the 19th February, in lat. 64° 37' S., long. 85° 49' E., the temperature of the surface- 

 water was 32°, and that of the air 30°. A large number of icebergs were in sight. At 

 a depth of 50 fathoms the maximum index, which before immersion registered 31°"4, 

 rose to 32° (the temperature of the surface water), and the minimum index fell to 

 29° - 2, indicating a colder stratum of water. At 100 fathoms the maximum index 

 rose to the temperature of the surface water, the minimum fell to 29° which was 

 slightly colder than that at the depth of 50 fathoms ; but as two other instruments 

 sent down to greater depths, which, therefore, passed through this cold stratum did not 

 register 29°, the temperature of 29° - 2 has been adopted for 100 fathoms. The maximum 

 index of the one thermometer sent to 300 fathoms rose from 33° to 33°'8, but as the 

 two sent to the bottom, which must have passed through this stratum, only registered 33°, 

 that reading has been adopted.' On the other hand, this might indicate that the stratum 

 of 33° "8 F. is so limited that the bottom thermometers passed through it without 

 attaining the full temperature. The bottom temperature at 1800 fathoms, as registered 

 by two thermometers, was between 33° and 29°. 



On the 21st February, in lat. 63° 30' S., long. 88° 57' E., and under the same circum- 

 stances of air and surface water temperature, a few observations showed a regular decrease 

 in the temperature from 32° at the surface to 29° - 3 at 40 fathoms. 



On the 26th February, in lat. 62° 26' S., long. 95° 44' E., the temperature of the air 

 was 35 0- 5, and that of the surface water 33°. A large number of icebergs were in sight. 

 Previously to immersion the thermometers were cooled with ice and salt to a low tem- 

 perature. At 100 fathoms the thermometer indices remained the same as on immersion, 

 viz., 31°"8 and 32°, although this temperature was lower than that of the surface water, 



