146 



DR HUGH ROBERT MILL ON THE 



cooling at the surface, but at the bottom the period of heating was 8 days shorter 

 than that of cooling. At Gantock, on the other hand, the surface water required 

 25 days, and the bottom water 18 days longer to heat than to cool. 



The contrast in this particular is the remarkable lengthening of the period of heating 

 and diminution of the period of cooling at the bottom in the enclosed loch ; or, since the 

 time required for a given change of temperature is the reciprocal of the rate of change, 

 the average rate of heating is smaller and that of cooling much greater in an enclosed than 

 in a relatively open basin. This is evidently due to restriction of circulation in the 

 water. 



Table LIX.— M ean Temperature at Various Depths in Dunoon Basin. 













Mean Temperatures. 







Section. 



Date. 



Interval. 

 Days. 

















Mass 

 (Wtd.). 



5 fms. 



15 fms. 



25 fms. 



35 fms. 



45 fms. 



55 fms. 



I. 



17.4.86 





42-12 



42-70 



41-85 



41-70 



41-50 



41-45 



41-40 



II. 



19.6.86 



62 



45-78 



47-75 



44-82 



44-17 



44-00 



43-94 



44-23 



III. 



6.8.86 



48 



49-33 



50-86 



48-64 



48-05 



47-89 



47-83 



47-40 



IV. 



26.9.86 



51 



52-74 



52-97 



52-80 



52-46 



52-27 



51-89 



51-85 



V. 



12.11.86 



47 



50-95 



50-43 



51-20 



51-36 



51-47 



51-54 



51-36 



VI. 



24.12.86 



42 



46-34 



45-62 



46-52 



46-99 



47-38 



47-46 



47-24 



VII. 



6.2.87 



44 



43-75 



43-00 



44-13 



44-32 



44-48 



44-50 



44-50 



VIII. 



24.3.87 



52 



43-28 



43-18 



43-26 



43-41 



43-50 



43-53 



43-60 



IX. 



7.5.87 



45 



44-86 



45-73 



44-42 



44-19 



44-10 



44-16 



44-27 



X. 



14.6.87 



38 



48-88 



51-00 



48-34 



46-79 



46-28 



46-13 



46-30 



XI. 



7.8.87 



44 



54-01 



55-80 



53-86 



52-09 



51-15 



50-82 



50-83 



XII. 



30.9.87 



54 



54-01 



54-19 



54-03 



54-01 



53-94 



53-85 



53-79 



XIII. 



30.11.87 



61 



48-26 



48-00 



48-50 



48-40 



48-35 



48-35 



48-30 



XIV. 



11.2.88 



73 



44-34 



44-28 



44-28 



44-47 



44-51 



44-55 



44-39 



XV. 



8.3.88 



25 



44-01 



44-30 



43-71 



43-88 



44-05 



44-12 



44-25 



XVI. 



28.3.88 



20 



42-29 



42-05 



42-43 



42-48 



42-46 



42-36 



42-38 



Fig. 50, Plate XXXII., gives the seasonal change of temperature of the air over the 

 Dunoon Basin taking this as the mean of the air at Greenock and Eothesay, of the 

 superficial 5-fathom layer of water, and of the layer between 30 and 40 fathoms, as well 

 as of the mass of water. The period represented comprises two maxima and three 

 minima. In their general form the curves resemble those of the Arran Basic and 

 Loch Strivan, showing the characteristic lag of the deeper layers in heating, and the 

 much less obvious lag of the deeper layers in cooling. 



The retardation of the period of maximum in the surface water (5-fathom layer) 



