72 DR HUGH 110BERT MILL ON THE 



maxima occurred about a month later in the Basin. The curve of air-temperature cut 

 that of mean water-temperature rather after the maximum, instead of before it, as in the 

 Channel. 



During the period of rising temperature, the air was warmer than the surface layer 

 of water for 147 days in 1886 and for 125 in 1887 ; while the air was cooler than the 

 water on 224 days in the cool season 1886-87, and 232 days in 1887-88, giving an 

 average of 134 days of air warmer than water and 228 cooler, comparing with 134 

 warmer and 237 cooler for the Channel, the cycle being somewhat over a year in this 

 instance. 



The surface-water curve in fig. 24 is compiled in a less satisfactory way than the 

 curve for mass temperature. It is nearly a mean between the mass curve and the air 

 curve during the period of heating, and shows a tendency also to occupy an inter- 

 mediate position at the minimum. During cooling, however, the surface and mass 

 water curves coincided in 1886, but the surface curve remained higher until near 

 the minimum in 1887. The former is probably the more characteristic form. 



Interpolating probable values for the first three months of 1886, we are able to arrive 

 at the following averages for the year : — 



In 1886, . . Air =46-2 ... Surface Water =47-4 ... Mass of Water =46 -4 



In 1887, . . Air =47-0 ... Surface Water =49 "3 ... Mass of Water =47-5 



The " surface " water being the top layer 5 fathoms deep. 



Here we see the mass of the water on the average of two years one-third of a degree 

 warmer than the air, while the surface water averaged 1°'7 warmer, thus closely 

 approximating to the condition in the Channel. It appears that on the average 

 of the whole year the Arran Basin exercises a warming influence upon the air, although 

 not to such an extent as the Channel. 



Loch Fyne. 



Loch Fyne is an extension of the Central Arran Basin so far as surface water is con- 

 cerned, but the depressions of which it is composed are barred off in such a way as to 

 isolate the deeper water more completely than in any other part of the Area. It may be 

 said that the deep water of Loch Fyne is more effectively isolated from the Arran Basin 

 than the Arran Basin is from the open sea. Within the Otter Bar the bed of Loch Fyne 

 deepens into the comparatively flat and shallow Gortans Basin scarcely more than 

 34 fathoms deep, which in turn is shut off from the deep Upper Basin by a ridge at 

 Minard, on which rises a series of islands separated by narrow channels. Beyond this 

 second barrier there is a steep descent to depths of over 75 fathoms, and then a gradual 

 rise to the head of the loch at Cuill. Numerous observations were made in Loch Fyne, 

 and both temperatrue and density were more fully studied there than in any other 

 division of the Area of equal size. Each station has a certain individuality with regard 



