136 DISCOVERY REPORTS 



were made frequently by comparison with insulating water-bottle measurements, and showed no 

 significant deviation from the original calibration. 



It was decided while planning the surveys that intermediate observations of temperature between 

 the lines of full stations would be invaluable in constructing a detailed picture of the upper layer 

 circulation. For this a bathythermograph was used. The instrument, the standard U.S. Navy pattern 

 manufactured by Wallace and Tiernan Prod. Inc., New Jersey, conformed to the specifications of 

 accuracy prescribed by the makers. (Temperature ±o-i° F. and pressure ±4^ ft. with a depth limit 

 of 450 ft.) Frequent calibrations of both temperature and pressure elements indicated a remarkable 

 constancy, and no correction of the results has been necessary. 



All water-samples were taken by standard methods, at the depths recommended by the Association 

 Internationale d'Oceanographie Physique. The Nansen-Pettersson insulating water-bottle was used 

 for sampling the shallower depths, as a rule not over 400 m., but on certain occasions it was operated 

 to a depth of 600 m. when an additional reversing hoist could be omitted thereby. At greater depths 

 Munro-Ekman reversing water-bottles were employed. Three of the latter were used in each hoist, 

 and while all carried two protected reversing thermometers, the upper and lower bottles were equipped 

 with unprotected reversing thermometers as well. 



Biological collecting during the surveys was mainly confined to standard series of plankton net 

 hauls. The nets used and method of fishing were similar to those employed during the pre-war work 

 of the Discovery Investigations (Kemp, Hardy and Mackintosh, 1929). The vertical series at full 

 stations in oceanic waters included hauls with the Nansen pattern closing net, 70 cm. diameter at the 

 mouth (N 70 V), at depth intervals of 50-0 m., 100-50, 250-100, 500-250, 750-500 and 1000-750 m. 

 At shallow water stations the series was modified so as to work as close to the bottom as possible. 

 A 100-0 m. vertical haul with the N 50 V phytoplankton net was also made. During the second 

 survey oblique hauls were made with the i-m. stramin net (N 100 B) and 70 cm. silk tow-net (N 70 B) 

 on 200 m. of warp, maximum depth being recorded by Kelvin tube, and a i-m. net (N 100 H) was 

 also towed horizontally at the same time. These were in addition to the vertical series. Towed nets 

 were not used during the first survey. In addition to the hauls at full stations, the N 50 V was worked 

 at all the intermediate bathythermograph stations on both surveys. 



A full-sized commercial otter-trawl (OTC) and conical dredge (DC) were used at a few stations on 

 the shelf during the first survey, and during the second, numerous bottom-samples were collected 

 with snapper-lead and Baillie rod. Full details of dates, times, etc., at which these types of gear were 

 used are given in the Station List (1953) which also includes full definitions of the standard abbrevia- 

 tions employed. 



The centrifuging of water-samples was not employed as a routine method for phytoplankton 

 sampling, but was used for provisional identifications of dominant organisms in areas of discoloured 

 water, whence surface-samples were preserved for subsequent analysis. 



It was important above all to extend the basic physical and chemical observations over the widest 

 possible area, and it was mainly for this reason that we did not attempt more comprehensive work on 

 the phytoplankton, and more particularly on the smaller organisms known to escape nets. The Harvey 

 method of pigment extraction from the catch of a fine-meshed vertical net fitted with a flow-meter 

 (Harvey, 1934), which had proved most useful in the antarctic zone (Hart, 1942) was not used because 

 it was already known from the 'Meteor' results (Hentschel, 1936) first, that dinoflagellates were of 

 vastly greater relative importance in this area than in the antarctic, and their mixed pigments tend 

 to vitiate direct visual colour match ; secondly, that the nanno-plankton forms would similarly be of 

 greater relative importance here. In the event, we found diatoms so numerous in the rich coastal belt 

 that the earlier form of Harvey's method would most certainly have yielded valuable results. More 



