THE HEART OF THE ANTARCTIC 



definite relation to the dimensions of the body of water. 

 Seiches are best observed in enclosed basins of water, where 

 they are not interfered with by tides, but oscillations of the 

 same nature are of frequent occurrence in deep bays on 

 the sea coast. These may be set up by the ordinary lunar 

 tides, but the recurring tidal waves may often obscure 

 them. The seiches at Cape Royds might originate in this 

 way. The Ross Sea is a deep bay of large size in which 

 secondary oscillations might be expected, and McMurdo 

 Sound is a similar bay of small dimensions. The seiches 

 observed, with periods of only a few minutes, and small 

 amplitude, might be supposed to be readily set up by 

 winds. 



Currents in McMurdo Sound 



There were many indications of a permanent current 

 setting south past Cape Bird towards Cape Royds. About 

 half a mile north of Cape Royds, at Black Sand Beach, 

 it was by some influence deflected, and left the land, 

 passing away southward for some miles. The readings 

 of the current indicator set up near Cape Royds seem 

 to show that the deflecting influence is another current 

 coming from the southward. 



The first indication of the southward setting current 

 was a pretty one. On March 16, when the Sound was 

 entirely open and no large ice was in sight, a strong 

 southerly wind was blowing. This brought a quantity 

 of fine broken ice with it which drifted along the shore 

 from Cape Royds northwards, forming a zone about one 

 hundred yards wide. In the figure the dark shading shows 

 the band of ice fragments, the small arrows the direction 

 of the wind, and the long arrow the currents from the 

 north which stopped the drift of the ice. 



At Black Sand Beach the band of ice left the shore 

 and swung round and went away across the Sound in a 



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