1097 



order to be able to mix these data together ijito one series, the 

 probable error of each series was determined and the amount of 

 the deviations for each winter expressed in it, so as to eliminate 

 the arbitrary element involved in the term "abnormality". For 



a ê 



each station the two series thus obtained for the values - and - 



d d' 



were finally combined and of these numbers the average was taken 



TABLE I. 



Curve from 13 periods of 89 years, 760-1916. 



