420 THE VOYAGE OF H.M.S. CHALLENGER. 



Owing probably to their having passed too quickly through I lie narrow bell of superheated 

 water. A third instrument which, before immersion, was set at 32"T> was afterward* 

 Bent to the same depth, when the maximum index registered 32 0, 8, or approximately 

 t lie surface temperature; and the minimum 81**8, Or the same temperature as previously 

 obtained. 'Plus reading has, therefore, been assumed as the temperature at 100 fathoms. 

 At 150 fathoms two thermometers registered a warm stratum of S I ", and the minimum 

 indices showed that they had passe. 1 through the cold intermediate stratum of 32°. This 

 was also confirmed by the two instruments lowered to 200 fathoms and the one sent to 

 the bottom, for each of them registered a maximum temperature of 34°, ami a minimum 

 of at least 31 c, 8. The bottom thermometer, indeed, registered on its minimum side 

 31 0, 3, but unfortunately its temperature on immersion was not noted, and as it was 

 cooled by the mixture of salt and ice. it may have stood at the temperat ure of 31°"3 

 when immersed. The bottom temperature is, therefore, uncertain, but must be between 

 34° and 81 6 -3. 



On the I 1 1 1 1 February, during the passage out liwanl. in lut. 00 ' ,">2 S., long. S0° 20 lv. 

 with three icebergs in sight, serial temperatures were taken. The temperature of the 

 air was 35°"5, and that of the sea surface 34 0, 2. Before immersion the thermo- 

 meters, with the exception of those sent to the bottom and to the depth of 25 fathom*, 

 were ct mled to as low a temperature as was deemed necessary. The lowest temperature 

 registered was 32° at f>0 fathoms, and this continued certainly tit the depth of 100 

 fathoms. At 150 fathoms the thermometer registered 3(5° on the maximum side and 

 31 'S on the minimum. At 200 fathoms the thermometers registered from 35° to 

 :;.") -S on the maximum side and 32" to 32 '8 on the minimum. At 300 fathoma the 

 thermometer gave the same result as at 200 fathoms. Here, therefore, a rise of 

 temperature took place at L50 fathoms, which reached its maximum at 200 fathoms. 

 The bottom temperature is uncertain, M the thermometers w Inch, on immersion, registered 

 41° came up showing 41" on the maximum and 82" and 33 on the minimum side. 



On the 3rd March, in hit. 53° 55' S„ long. 108°35'E., the temperature of the air 



being 37°"8, and that of the sea surface 87**2, serial temperatures Were again obtained. 

 No icebergs were in sight, but some were seen on the 2nd, and one was passed on the 4th. 

 The thermometer* were lowered to every 10 fathoms from the surface to 100 fathoms. 

 and showed little alteration to the depth of 60 fathoms, registering there ,'!('> "•(>. or 

 Only 0' '■(> less than the surface temperature. At 70 fathoms a sudden fall of 3 J," took 

 place, and at SO fathoms the temperat lire was 32"\">. below this depth the temperature is 

 uncertain, as the instruments registered on their maximum side the temperature of 

 immersion, and on their minimum the temperature at SO fathoms. If a stratum of warm 

 water commenced at 150 fathoms of the same temperature as that iA' the 20th February, 

 viz., 34", as there is every reason to believe, it could not, owing to the construction 

 of the instruments, be detected, for, as the thermometers had passed through the 



