42 



DISCOVERY REPORTS 



These values have been used to obtain the relative heights of the sea surface at the 

 stations of the November survey, and have been entered in column 4 of Table IV. 



Table IV 



Now St. WS 482 is a very shallow station, the bottom depth being 152 m., and in the 

 preparation of a series of topographic charts it is better to choose as a basic station one 

 whose depth is at least equal to the greatest depth represented in a chart of dynamic 

 topography. Since all the values in column 4 are purely relative, any station may be 

 arbitrarily chosen as the basic station, and in column 5 of the above table St. WS 480 

 has been thus selected and the values at the other stations correspondingly altered. 



The lines of stations in December 1930 from Cape Melville to Trinity Peninsula and 

 from between Elephant and Clarence Islands in the direction of Joinville Island were 

 linked by direct comparison of the dynamic depths to the 2000 decibar surface. In this 

 case St. 543 was chosen as the basic station, and Table V contains the heights of the sea 

 surface of the other stations relative to this station. 



It has been previously mentioned that the results from November 1929 would if 

 possible be linked with those of December 1930, so as to obtain a more complete 

 picture of the water movements. By inspection of the vertical sections of the anomaly 

 of specific volume for the two lines from King George Island in these two years, it was 

 assumed that at 2000 m. the specific volume anomaly in each case was 10 x io~ 5 and 

 that no current existed at this depth in either year. Then, by a direct comparison of the 

 dynamic depth to the 2000 decibar surface for St. WS 478 in November 1929 and 

 St. 543 in December 1930, we have the following relation for the difference of level in 

 dynamic cm. of the sea surface at these two stations : 



WS 478-St. 543 = 7-25 dynamic cm. 



