192 



PRESSURE. 



on April 15, -nhich, if we had this curve alone, we misht take as the maximum of a sur<Je ■ 

 but it will be noticed that while it is just recognisable on the Cape Adare curve, it would 

 not be chosen as the maximum of a surge from that curve. 



Such difficulties would not be of so much importance if there were more surges available 

 for measurement ; but with only about ten surges recognisable on each curve the result is 

 easily affected by personal bias. It was decided therefore to employ a method as free as 

 possible from personal choice. The procedure followed was the following. For the statistical 

 discussion of these surges (see page 190) it was necessary to consider only surges which 

 were greater than -2", and each maximum and minimum which fulfilled this condition was 

 tabulated. The maxima and minima thus chosen were marked on the curves of plate I with 

 the signs + and — respectively. 



When this had been done, only those maxima and minima were considered which were 

 marked on all three curves, or those which were marked on two curves and the corresponding 

 maximum or minimum was clearly visible on the remaining curve although not marked. 



Six comi^lete surges were thus marked, commencing with the minimum on April 8 and 

 ending with the minimum near December 11. Each of the maxima and minima are tabula- 



ted in the following table : — 



Table 112. 



Pressure surges in Ross Sea area. 



This table shows that the mean amplitudes of the waves which can be recognised on 

 all three curves are : — 



Cape Adare . 



Cipe Evans . 

 Fiamheim 



Mean amplitude 

 max.-min. 



•376' 

 -400" 

 -419" 



The surges are too few for any .stress to be placed on the actual values ; but considering 

 that the result has been obtained by a method which reduces personal bias to a minimum. 



