174 



PRESSURE. 



that month could not be far from 29-42". Taking this value \vc have now two complete 

 ■sets of mean monthly pressure from March to January. February is therefore the onlv missing 

 month, and we cannot do better tlian take for this jnontli the mean of t-lu^ values for .Tanuarv 

 and March. Completed in this way we have the following two years' pressure data for Cape 

 Adare, the values not actually observed being entered in brackets. 



Table 98. 

 Mean monthly 'pressure at Cape Adare. 

 Reduced to 32°F., sea-level and gravity at 4.5°. (Inches.) 



In addition to this determination of the yearly pressure variation at Cape Adare based 

 on two incomplete years of observation we are able to reduce the four years' observations at 

 McMurdo Sound to Cape Adare by means of the ten months' simultaneous observations in 

 1911. 



The monthly differences Cape Evans — Cape Adare are given in the last column of table 

 95, page 171, and they are plotted in curve II of figure 57.* It will be seen that the 

 points lie on a curve similar to the one found for Framheim, but that the amplitude is 

 much less. The first line of the following table gives the values of the smoothed difference 

 measured from the curve and in the second line these differences have been applied to the 

 normal pressure of McMurdo Sound to obtain the normal pressure at Cape Adare. 



Table 99. 



Normal pressure at Ca-pe Adare as determined fro)n four years' observations in McMurdo Sound 



and I lie smoothed difference found in 1911. 



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



The values for the yearly variation found by the two methods, table 98 and table 99, 

 are shown in the thin and thick curves, figure 55(6). The two curves are similar, varying 

 appreciably only in July and tlie summer months. The liigh value on the thin curve for 



.* The differences for May and June have been combined as individually they lie ratlier far froui tlie c-uive, 

 but comliini'd fit -well witli the other points. 



