THE SCARCER FISHES IN ABERDEEN MARKET 



241 



exception on the map, but it is so slight that it may be 

 looked on as one of those exceptions that are said to prove 

 the rule ; for his fish were caught in the second week of May, 

 only a fortnight beyond our seasonal limit. 



We may, however, by using a statistical device of 

 averaging and of " smoothing," bring a good deal more out 

 of these seasonal data. Let us take, for each square, the 

 average date of the captures therein. For instance, in 

 the area (K) north and north-west of the Lewes, we 

 have had captures in June (6), July (7), August (8), and 



Fig. 3. Approximate Seasonal Distribution of Chimera, based on the 

 Average Dates of Capture in Contiguous Squares. 



September (9); the mean is 7-5. Let us call it, in round 

 numbers 8, and ascribe it to it. We shall find that these 

 average dates for the several areas group themselves in 

 a fairly orderly way upon our map. But let us further 

 " smooth " them by taking a mean value wherever four (or 

 three) areas meet at a point ; that is to say, let us replace the 

 values within the squares by mean values at the corners, or 

 junctions, thereof. This I have done in Fig. 3, and the 

 result is remarkable. We see a steady tendency (it is of 

 course no more than a tendency, and is subject to exceptions) 

 for the average dates of the occurrence of Chimaera to get 

 later and later, as we pass along our belt of stations from 



