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Part III. — Fifteenth Annual Report 



showed that the minimum in the shallow water was at 15 fathoms, and 

 that the w T ater on the west, or Tarbert side, was slightly warmer than that 

 on the east side, but the difference was scarcely half a degree. 



On the 4th and on the 6th a complete series of observations was taken 

 at intervals or about 5 miles along the whole length of Loch Fyne ; and 

 it was found, as had been anticipated, that the differences in temperature 

 were not sufficient to make tidal observations of any certain value. The 

 two sections may, however, be compared. The average temperature of 

 the whole water in Loch Fyne was close to 45° '1 on the 4th, and about 

 45° "2, or rather less, on the 6th, showing the progress of seasonal warm- 

 ing. The Gortans Basin was filled with water averaging 44° - 8. This 

 colder water seemed to project like a double wedge into the warmer 

 water of the Upper Basin, one tongue of the wedge forming a thin layer 

 traceable right up to Cuill at the depth of about 7 fathoms, the other, 

 a thicker layer, traceable to Iuveraray at a depth of about 25 fathoms. 

 The warm layer separating the two tongues was traced as far down the 

 loch as Furnace in 17 fathoms, but the difference in temperature was too 

 slight to serve as a test of the movement of the water. 



Chemical Conditions of the Water. — Thirty samples of water were 

 collected on this trip, and analysed by Mr H. K. Dickson in the Labora- 

 tory of the University of Oxford, who has furnished Table II., containing 

 the analyses showing density determined by Sprengel-tube weighings, 

 amount of chlorine (x), and of sulphuric acid (S0 3 ), as well as the ratios 

 between the various quantities. 



The salinity translated into percentages of pure sea-water for the whole 

 depth, at each station, is as follows : — ■ 



dull, Dunderawe, Inveraray, Straclmr, Furnace, Gortans, Otter, Skate Island. 

 85*7 89-3 93-4 93"6 93'6 93"9 94'2 96'4 



The formula given in my paper on the salinity of the Clyde Sea Area, 

 for the calculation of the average salinity from bottom and surface 

 observations, is erroneous. The above figures are obtained on the basis 

 of the series showing three intermediate samples at Straclmr, the bottom 

 density being given eight times as much weight as that at the surface, 

 except in the shallow water, at Cuill, where the bottom density is weighted 

 only five times. 



The salinity was well within the range previously observed, and not 

 far from the average. 



With regard to the composition of the water, the ratio of sulphuric 

 acid to chlorine appears almost always to be greater at the bottom than 

 in the surface water, but in other cases the contrary holds good. The 

 high ratio of sulphuric acid in Nos. 24 to 29 is difficult to understand. 

 If the figures convey any physical meaning, it would appear that the water 

 at Strachur had undergone some change of composition between the 

 4th and 6th of April. It certainly seems that some accident had 

 happened to the samples by which sulphates had been introduced, 

 especially as the only sample showing a similarly high ratio was one 

 collected about a week later from the surface off the Mull of Cantyre. 



Trip of September 1896. 



On September 3rd I joined the ' Garland ' at Inveraray, and left on 

 September 12th at Gourock. The following is an abstract of the work 

 done : — 



September 3rd. — Observations at Inveraray and Dunderawe, and tidal 



