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Part III. — Seventh Annual Report 



Three years later, in August and September, a second batcli of samples 

 was collected from the, same locality. The results obtained with these 

 samples were altogether unexpected. 



This time also, the values found for D were remarkably uniform, but 

 quite different from those found in 1883. In the 45 samples examined, 

 the value for D ranged from 1-4735 as a maximum to 1*4675 as a 

 minimum, the mean value being 1*4710. 



In my last Report, sample 26, being a bottom water collected be- 

 tween the Sutors at the entrance to the Cromarty Firth, appears as 

 exhibiting an altogether abnormal value for D, viz., 1-536. This result 

 was seemingly confirmed by the results obtained with two samples 

 collected in May 1888, from or close to the same place. In Table 

 V. of the same Report, the two samples Nos. 46 and 47 show values 

 for D approximating to that attributed to sample 26, viz,, 1*5481 and 

 1*5466 respectively. At the time there appeared no sufficient grounds 

 for rejecting these results, but as the data which appear in the following 

 tables gradually accumulated, my suspicions regarding these results were 

 again aroused. I was thus led to the discovery of errors of calculation 

 affecting these three results. The misplacement of a decimal point at one 

 stage of the calculation of the total halogen of No. 26, and the insertion 

 of the weights of distilled water not corrected to vacuo in the calculation 

 of the specific gravities of samples 46 and 47, led by a curious coincidence 

 to these three altogether incorrect and yet concordant results. The correct 

 values are 1*4725 for sample 26, and 1*4720 and 1*4700 for samples 46 

 and 47 respectively. These correct results are in perfect agreement with 

 the other 44, so that there is no longer the same reason for considering 

 the water from this particular locality as being altogether different from 

 the mass of the waters in the Moray Firth generally. 



N evertheless, as will be seen later on, this very spot exhibits peculiarities 

 which, if not so altogether abnormal, are still interesting, and looking back 

 I do not regret that my attention was thus specially directed to it. 



These apparent local abnormalities being thus cleared away, the general 

 bearing of the results arrived at so far remains to be considered. 



The first conclusion -to be drawn from the results obtained with these 

 two sets of samples is, that whatever influence the proximity of land 

 may have on the composition of the waters of the Moray and adjoining 

 Firths, it cannot account for the remarkable difference between the 

 composition of these waters at the two periods in which the two sets of 

 samples were collected, viz., August and September 1883 and August 1886. 

 This is evident from the fact that, although the values for D are so 

 very different in the one set of samples as compared with the others, it is 

 nearly constant in each set. Moreover, the samples of low specific gravity 

 collected at points where the influence of rivers is necessarily greatest, 

 show no such differentiation as would in any degree account for the 

 remarkable difference in the composition of the two sets of samples. 



The second conclusion to be drawn from these results is, that the sea 

 water present in these Firths at the time of the first expeditions in 1883 

 was quite distinct from that present at the time of the expedition of 1886, 

 and that this generic difference extended from the sea inwards to the 

 farthest reaches of the inland firths, and from the surface to the bottom, 

 without exception. 



The explanation of this remarkable fact may be derived from a con- 

 sideration of the results obtained during the last year. The data given in 

 Table IV. relating to the samples collected during the cruise of the ' Jackal ' 

 in September and October last, show that both kinds of sea water were 

 present in the North Sea at that period, but in different parts of it. 



