were not overblown by snow, the vehicle tracks on the trail were our 

 best means of direction. 



A snow vehicle, the Polecat, (Plate XXV) was maintained for the 

 exclusive use of this project, a precaution which, when possible, 

 insures that a vehicle in good running order will be available most 

 of the time, at least. The Polecat is an articulated vehicle built 

 on two sets of weasel tracks and undercarriages, all four tracks 

 being power-driven by a 130 h.p. International Harvester motor with 

 manual gear shift. It had a very low ground pressure and was excel- 

 lent for our purposes in every respect. It gave, and is still giving, 

 very reliable service. New specially constructed tracks good to 

 -60°F. , which were installed just previous to the author's departure 

 from McMurdo, should prove adequate for all except the very occasional 

 extremes of temperature on the ice during the winter. During the 

 following winter, the new tracks were used without any difficulty 

 in temperatures as low as -68 F. It also should be mentioned that 

 the Polecat was the one snow vehicle which could be depended upon 

 during the second winter of operation when it was used by biologists 

 from Stanford University. 



B. Water Samples 



Water samples were obtained with standard Nansen bottles placed 

 6 to a cast; 3 casts were made at each station, thus obtaining in- 

 formation at all standard depths plus some additional depths. Paired 

 protected reversing thermometers on each bottle were used for water 

 temperatures. Unprotected thermometers were not used because of the 

 comparatively shallow depth and also because with the heavy weight 

 used, there was rarely any wire angle. Wire angle sometimes gave 

 trouble when using the Ekman current meter with its much lighter 

 weight, and care had to be exercised in raising the meter past the 

 bottom edge of the sheet metal lining of the icehole. Having a 

 warm (usually too warm) hut to work in, there was no trouble with 

 water samples freezing in the Nansen bottles and having to be 

 brought into the laboratory for thawing out, a situation much de- 

 plored by the Australians (Bunt, 1960). Thermometers were read as 

 soon as they reached room temperature after the water samples had 

 been taken and the bottles drained. 



C. Dissolved Oxygen and Salinity 



Samples for oxygen determination were collected in ground glass- 

 stoppered bottles and titrated in the laboratory. Salinity samples 

 were drawn off in Citrate of Magnesia bottles and sent back to the 

 Hydrographic Office where more accurate determinations were made. 

 Bathythermograph drops were made to about 900 feet at each station 



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