6 



Fishery Board for Scotland. 



The average value of tlie odd inches will be, in the long run, 

 + 1+2 + 3 ■ . .+11 _ 66 

 ~12 



12 



or 5'5 in., i.e. "46 of a foot. Takinar at 



random the month of December 1907, in which month we had 118 

 readings of high and low water at Aberdeen, we find that the indi\4dual 



J F M 



MY. J JY. A 



FEET 

 ■4 



— / 



- 2 - 



-J 



Fig. 2. — Mean High Water Level : Dundee and Aberdeen. 



readings were as follows, as regards the number of odd inches 

 recorded : — 



Inches: 12 3 4 5 6 7 8 9 10 11 



No. of readings : 17 4 8 18 4 5 17 10 7 14 7 7' 



the mean value of these being 616/118=5'22 in., or only '28 in., 

 or "023 ft., short of what we might expect in a long series, from the 

 law of averages. 



But if we assume that the recorded readings at 0, 3, 6, and 9 in. 

 will be, say, twice as numerous as those at the intermediate points, 

 an assumption which is not far off from what we actually find to be 

 the case, then, in a long series, the mean of the recorded inches will 



