140 



MR R. C. MOSSMAN ON 



mean of the month, diminishing to 29 '33 inches at the South Orkneys, and still lower to 

 the eastward. The month in its main features bore a very close resemblance to that of 

 December 1904, which I have treated with some detail in the paper on the Weddell Sea 

 meteorology. 



It will be seen from the foregoing brief synopsis how the climatic conditions over 

 South America vary according to the position of the southern "centres of action." It 

 is not sufficient, however, to confine our investigation to the Southern Hemisphere, 

 because there is an intimate relation between both hemispheres. For example, the 

 cyclonic " centres of action " situated in the Weddell Sea and in the Icelandic region 

 stand at certain periods of the year in a definite relation to each other. In the month 

 of May, in which that relation appears to be most pronounced, a positive departure 

 from the normal barometric pressure at Stykkisholm (Iceland) is a direct index of a 

 negative deviation from the normal in the pressure over a region to the south-east of 

 and including Cape Horn. When there is a positive deviation over this latter area, 

 then the departures in the Icelandic region are negative. This, be it understood, applies 

 only to the month of May, and is based on twenty years' data from Cape Horn and six 

 years' data from the South Orkneys ; but the whole inquiry is in an early stage of 

 development, and further interesting contrasts are to be expected from a discussion of 

 bipolar conditions. 



Table I. 



Percentage Frequency of Wind at Point Galera, Lat. 40° 01' S., Long. 73° 44' W. 

 7 Years 1899-1905. Hours of Observation 8-2-9. 



N. 



Jan. 



Feb. 



Mar. 



April. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Year. 



20 



20 



30 



42 



47 



45 



32 



33 



28 



13 



19 



15 



29 



N.E. 



1 



1 



1 



3 



5 



5 



4 



3 



2 



1 



1 







2 



E. 







1 



2 



1 



7 



6 



6 



5 



3 



1 







1 



3 



S.E. 



1 



2 



3 



5 



2 



2 



6 



5 



3 



3 



2 



2 



3 



S. 



52 



51 



36 



18 



10 



9 



9 



9 



20 



34 



32 



52 



28 



S.W. 



11 



9 



9 



6 



3 



5 



7 



8 



8 



16 



li 



10 



8 



W. 



5 



2 



4 



4 



4 



4 



9 



8 



11 



10 



6 



6 



6 



N.W. 



5 



4 



4 



10 



15 



16 



22 



22 



20 



15 



21 



7 



13 



Calm. 



5 



10 



11 



11 



7 



8 



5' 



7 



5 



7 



8 



7 



8 



Table II. 



Percentage Frequency of Wind at Ancud, Lat. 41° 51' S., Long. 73° 50' W. 6 Years 1900-05. 



Hours of Observation 8-2-9. 



N. 



Jan. 



Feb. 



Mar. 



April. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



11 



Year. 



9 



10 



16 



15 



11 



14 



10 



13 



18 



11 



11 



12 



N.E. 



1 



3 



2 



7 



12 



14 



13 



9 



5 



4 



3 



4 



6 



I. 



2 



1 



4 



4 



8 



8 



5 



3 



3 



2 



2 



2 



4 





3 



4 



5 



5 



15 



11 



11 



6 



6 



4 



3 



2 



6 



8. 



9 



13 



12 



15 



12 



13 



11 



12 



9 



12 



9 



8 



11 



8. W. 



10 



9 



8 



6 



4 



6 



5 



6 



5 



8 



7 



10 



7 



W. 



25 



24 



18 



12 



8 



10 



13 



16 



19 



28 



25 



24 



19 



N.W. 



22 



18 



17 



17 



16 



15 



14 



24 



24 



20 



27 



19 



20 



Calm. 



19 



18 



18 



19 



14 



9 



18 



11 



11 



11 



13 



20 



15 



