44 



A Retrospect of Oceanography 



had to be run out and hauled in ; then 700 fathoms ; then one 

 or perhaps two shorter lengths, according to the number of 

 temperatures near the surface which were desired. This 

 service alone entailed the handling of something like 2500 

 fathoms of line, and, as we have seen, during the whole voyage 

 only two accidents occurred to the temperature line. The 

 following table shows the work which was done by the 

 temperature line. 



The number of stations which furnished these 4899 

 temperature observations was 262, which gives an average 

 of 18-7 observations per station. A full station in deep water 

 included either three or four operations and furnished from 

 20 to 30 temperatures. At many stations the depth was less 

 than 1500 fathoms, and it was not necessary always to take 

 temperatures at such close intervals. The main result of 

 the above table is to show that the enormous number of nearly 

 five thousand deep-sea temperatures was obtained with an 

 expenditure of only eight thermometers and one line. It was 

 at the rate of 612 observations for every thermometer lost. 



Although specimens of the earliest pattern of Negretti 

 and Zambra's reversing thermometer were received on board 

 the "Challenger" before the end of the voyage, all the tempera- 

 tures above referred to were taken with the Millar-Casella 

 maximum and minimum protected thermometer. It is owing 

 to the use of this instrument that the temperature work of 

 the "Challenger" during little over three years is comparable 



