of the Fishery Board for Scotland. 



263 



although, in other years, few herring are to be found. The form of the 

 land bordering Loch Fyne has greatly restricted its drainage area, as 

 considerable rivers run parallel to the loch on both sides, draining the 

 country into Loch Crinan and Loch Riclun respectively ; thus, the only 

 streams of any importance enter near the head of the loch. 



The tidal current, according to the Admiralty publications, enters Loch 

 Fyne at Otter at the rate of 3J knots, passes through the Gortans Basin 

 at 2 knots, increasing to 2 J at Miliar J Narrows, but then slackening, 

 until off Dunderawe, near the head of the loch, it is reduced to 1 knot. 



From the earlier observations, it was shown that when the water of 

 Loch Fyne was at its saltest, the surface density increased from 1*02420 

 at the head (dull) to 1 -02486 at Otter, which was almost equal to that 

 in the open sea. When at its freshest, the surface density varied from 

 1*0114 at the head to 1*02383 at Otter, the density in the open sea (off 

 Can tyre) at the time being 1*02470. This considerable range of salinity 

 seems to be quite superficial, as the bottom density at the head of Loch 

 Fyne has only been observed to vary from 1*02359 to 1*02463 ; at Otter 

 from 1*02451 to 1*02507 ; and in the open sea near Canty re from 

 1*02469 to 1*02537. For purposes of comparison, however, it is more 

 convenient to take, as a standard of salinity, the percentage of pure sea- 

 water {i.e., of water with a density of 1*02000 at 60°F.), at each station 

 in the loch, taking the average from surface to bottom. At the entrance 

 to the Clyde Sea Area off Cantyre, this percentage was found practically 

 invariable as 97*6. In Loch Fyne it increased from 88*3 at the head to 

 95*1 at Otter, i.e., on the average, 0*26 per cent, of sea-water per mile. The 

 extreme range observed at the various stations in Loch Fyne, with Skate 

 Island (off Tarbert) added for comparison, was as follows : — 





CuilL 



Dunder- 

 awe. 



Inver- 

 aray. 



Strachur. 



Furnace. 



Gortans. 



Otter. 



Skate 

 Island. 



Max. 



942 



95*4 



95'0 



95*0 



95'1 



95*5 



96*0 



96*9 



Min. 



80*4 



87*7 



90*8 



90*8 



91*6 



92*0 



93*4 



94*2 



Range 



13*8 



7*7 



4*2 



4-2 



3*5 



3*5 



2*6 



27 



These observations show • that there is no tendency for the accumula- 

 1 tion of fresh water in Loch Fyne ; the average salinity appears to come to 

 ' a maximum in June and July, the months of least rainfall and most 



• evaporation, and then to diminish steadily to the month of February, at 

 ' the period of maximum rainfall and minimum evaporation. Evaporation 

 - is probably the most potent factor in carrying away any excess of rainfall 



• during the summer months. A great accession of fresh watfi,r on the 

 ' surface must necessarily, by raising the level, accelerate the ebb-tide, and 



• so run off an excess of fresh water with considerable rapidity. On the 

 ' other hand, after a long dry spell, the tendency of evaporation would 

 ' be to lower the general level, and so accelerate the flood-tide, thus 

 ' increasing the salinity from without.' A brief discussion of the 

 circulation of Loch Fyne, with regard to salinity observations, showed 

 that the tidal effects were by no means superficial, but extended to the 

 bottom in the Gortaus Basin, although no evidence could be found of a 

 similar effect in the Upper Basin. 



Observations of salinity had given clear indications of the power of 



