368 



DISCOVERY REPORTS 



STATIONS OF THE R.R.S. 'DISCOVERY IT IN THE 

 MERIDIAN OF 8o°W 



Before the ' Discovery II ' sailed in 1933 on her third commission it was felt that some 

 more precise information was needed on the seasonal changes which take place in the 

 physical and biological conditions in 

 Antarctic waters. It was therefore de- 

 cided to make a series of observations 

 on a fixed line, and to repeat them 

 several times during the commission. 

 Such repeated observations are not only 

 required for the examination of seasonal 

 changes. They are of value in the study 

 of the cause and effect of any pheno- 

 menon of oceanic distribution. 



Since the normal conditions in the 

 Southern Ocean naturally vary much 

 more from north to south than from 

 east to west it was evident that the most 

 comprehensive results would accrue 

 from a line of stations running north 

 and south along a fixed meridian. For 

 several reasons the meridian of 8o° W 

 was chosen for this purpose. Here the 

 Antarctic zone is comparatively nar- 

 row and can be traversed in a short 

 space of time, and the currents are less 

 affected by disturbing land masses than, 

 say, in the neighbourhood of the Scotia 

 Sea. It was possible also to make re- 

 peated visits to this particular region 

 without sacrificing other projected work 

 in the Atlantic and Pacific sectors. 



During the whole commission five 

 lines of stations were worked in approxi- 

 mately 8o° W. These were in Decem- 

 ber, 1933, and in March, September, 



6O 



Fig. 1. Positions of stations in So W. 



October and November, 1934. Some details of the stations are given in Table I, and 

 their positions are shown in Fig. 1. It was our practice each time to work two stations 

 a day, one at 9 a.m. and one at 8 p.m. At each station temperatures and water samples 

 were taken at the usual depths (see Station Lists in the Discovery Reports), though at 



