530 EEPORT— 1886. 



I. II. III. IV. 



Deep temperature in April . . 41-8° 41-3° 41-5° 41-5° 



„ „ June . . 46-7° 43-9° 43-8° 45-3° » 



Rise of temperature .... 4-9° 2-6° 2-3° 3'8° 



To groups III. and IV. analogues are found in a deep and a shallow basin of 

 L/Och Lomond, in both of which the bottom temperature rose between April and 

 June. From this it is inferred that land-influences, especially drainage en masse, 

 produce most of the effect noticed in III. and IV. 



The great rise in the North Channel and southern plateau is evidently due to a 

 warm oceanic current. 



The rise in temperature in group II. is due to the incoming of warm water 

 from without. As the water between 30 and 75 fathoms Ln this group is very vmi- 

 form in temperature, and as the south plateau is 25 fathoms below the surface, it 

 is supposed that the dense plateau water is carried into the open basins (group 11.), 

 and through convection mixes thoroughly the water below 30 fathoms there. 



Loch Goil is specially remarkable for its isolation and the small rise of bottom 

 temperature — 0'6° F. in two months. 



In Upper Loch Fyne a lenticular mass of water below 43*0° F. was found in 

 June to float between two warmer layers. Its greatest thickness, 30 fathoms, 

 ■was opposite Inverary. The bottom layer of 44'0° F. was not found to be in con- 

 nection with any equally warm layer either inside or outside of the loch. 



10. On the Temperature of the Biver Thurso. 

 By Hugh Robert Mill, D.'Sc, F.B.S.E., F.C.8. 



Temperature has been observed since October 1885 twice daily at three points on 

 this the earliest salmon river in the north of Scotland. A shallow feeding lake nine- 

 teen miles from the sea, a point twelve miles from the sea, and one near the river 

 mouth, were selected for observations. At any given time the different parts of the 

 river preserved nearly the same temperature, varying slightly according to the 

 amount of sunshine and direction of the wind. The water cooled down from 

 October to January, and rose steadily in temperature as the season advanced. 

 Diurnal variation was least in January, and increased during each subsequent 

 month. The water, colder than the air at the time of observation during winter, 

 became warmer than it in summer. Shallow water responds more rapidly than air 

 to sun-heating and to chilling by radiation, a fact accountable for by its greater 

 absorbing and conducting powers. The sea was warmer than the river during 

 winter, and cooler than it during summer. 



Most of the observations discussed were made by Mr. John Gunn, Dale, and 

 Mr, David Gunn, Thurso. 



11. On the Normal Forms of Clouds. By A. F. OsLEE, F.B.S. 



The object of this paper is to explain a theory with regard to the principles 

 that may have the greatest effect in producing the leading forms that clouds 

 assume. 



There are doubtless many additional influences that produce or ^roTpagate further 

 changes and variations in these forms, but which may be regarded as exceptional 

 or occasional, through frequent disturbances of the regular action herein specially 

 referred to. These remarks will therefore be confined to those influences and 

 conditions that may be regarded as constant and uniform in their effects within 

 certain limits. They are simple and recognised physical causes, varying only in 

 amoimt and intensity. They may be classed under three heads : — 



1st. The diminished specific gravity of the air when more or less charged with 

 invisible vapour. 



2nd. The differential horizontal motion of the atmosphere. 



' Average temperature of first few fathoms above bottom. 



