312 



/ 



For the probable error of the c.c, Pearson gives the formula 



1— r" 



\/ri 



It holds good for the case of normal distribution of deviations 

 and the c.c. is considered to be reliable when /' is considerably 

 smaller than the c.c. itself; in the following tables 



'/ = '■/ƒ• 



3. The monthly mean values of barometric height in Iceland and 

 the region of the Azores are compiled from Danish and Portuguese 

 annals for the 36 years 1875 — 1910. 



The Iceland values are obtained by taking the average of three 

 stations namely : Berufjord, Grimsey and Stykkisholm. 



From the Portuguese observations average values were calculated 

 for two stations: Punta Delgada (Azores) and Funchal (Madeira); 

 for the A ears 1906 — 1910 Horta was .substituted for F'unchal. 



The monthly means thus obtained and considered as normal 

 values, are shown in Table 1 ; they are uncorrected for height above 

 sealevel, this correction being unnecessary for the calculation of 

 deviations, and given only to show the correspondence existing 

 between the annual variation of the ditferences of pressure and the 

 c.c. of table II. 



TABLE I. 

 Monthly means of atmospheric pressure 1875—1910, lOO mm. + 



It appears from these data that the differences of atmospheric 

 pressure are greatest in the winter months and smallest in May. 

 Table II shows the results of the calculation relating to the deviations 

 from the normal values of table I. 



