MONTHLY MEANS. 



171 



Coiiiparisoa of the fresmrc at Cafe Evans, Framheim and Cape Adare.-^The following 

 table gives the simultaneous mean monthly pressure reduced to sea-level and gravity 

 at latitude 45° at Cape Evans, Framheim and Cape Adare. 



Table 95. 

 Mean monthly pressure. 

 Reduced to 32°F., sea-level and gravity at 45°. (Inches.) 



These values are plotted on figure 56 and it will be seen at once how closely related 

 are the pressure changes at all the three stations. The series contains only ten months' 

 observations for Framheim and Cape Adare and these, extending over less than a year, are 

 not sufficient to give either the mean pressure for a complete year nor the yearly variation, 

 but by the aid of the close relationship between the pressure at the three stations it is 

 possible to amplify the data, and in the following two sections approximate values of the 

 normal pressure and the yearly variation will be obtained for Framheim and Cape Adare by 

 the aid of the more complete data for McMurdo Sound. 



Framheim. 



The pressure differences between Cape Evans and Framheim for each month are entered 

 in column 5 of table 95. There is a large yearly variation in the pressure difference, 

 the difference being largest in September and least in January. When the differences 

 are plotted (curve I, figure 57 ) it is seen that they lie approxiinately on a curve which 

 is much more regular than the curves of the pressures themselves. 



This curve is so regular, being almost a sine curve, that it is reasonable to conclude 

 that the two missing values for February and March if they had been available- would have 

 been on or near the curve. We may therefore use the values given by the curve for supply- 

 ing the missing data. According to the curve the diSerence between the pressure at the two 

 stations in February and March is 03" and 05" respectively. Applying these differences to 

 the pressure for February and March 1911 at Cape Evans, we obtain the following values for 

 a complete year's observations at Framheim. 



