36 



Fishery Board for Scotland. 



obtain will clearly indicate any progressive or cumulative tendency 

 which there may be towards increase or decrease, but will be entirely 

 freed from the periodic annual fluctuations which (as, for instance, in 

 Fig. 1) were apt to complicate the case. 



The following Table (W) exhibits, after this fashion, the average 

 catch of cod in Areas XXIII. and XXIX. from 1903 onwards: each 

 number, that is to say, signifying the average catch in cwts., per 100 

 hours' fishing, during the whole preceding twelvemonth, or (strictly 

 speaking) the mean of the twelve preceding monthly averages. 



TABLE W. 



Average Catch of Cod, in Cwts., per 100 Hours' Fishing, by Aberdeen 

 Trawlers. Each Figure represents the Average for the Whole 

 preceding Year ; i.e. the Mean of the Twelve preceding Monthly 

 Values {see also Chart, Fig. 4, following p. 41), 



The continuous curve representing this series of numbers is 

 easily drawn, and we need not print it; its main features are 

 sufficiently set forth in the simplified diagram (Fig. 4), which is 

 constructed from the December values only, and shows (that is to 

 say) merely the annual mean values for each calendar year. 



