132 



DK HUGH ROBEUT MILL ON THE 



the basin. The constancy of the Sprungschicht at 18 fathoms, as shown in the sections, 

 and the striking change in the form of the curves of vertical distribution of temperature 

 at 20 fathoms, indicate that the circulation takes place mainly in the upper half of the 

 water ; but the homothermic change of the lower half tells us that there is circulation 

 regularly in operation to the bottom. The retardation of the maximum is proof enough 

 that this circulation is restricted and gradual in its operation. 



The average temperature of each section was ascertained by measurements on the 

 section in the manner explained on p. 10. Tables LII. and LIII. give the weighted 

 mean temperature of each section, and the estimated mean temperature of each slice of 

 1 fathoms, as well as the rate of change of temperature between successive sections. 

 The figures so tabulated arc rendered graphically in the curves of fig. 48, Plate XXXI. 

 The air- temperature given in fig. 48 is the mean of that at Helensburgh and Callton 

 Ator, this probably representing some approximation to the actual air-temperature over 

 the loch itself. 



Table LII. — Mean Temperatures at various Depths in Loch Goil. 



Trip. 



Date. 



Interval. 

 Days. 



Mean Temp. 



of Mass 

 "Weighted. 



41-84 



Diff. 







Mean Temperatures of Layers. 



0-10 fms. 



10-20 fms. 



20-30 fms. 



30-40 fms. 



I. 



13.4.86 





42-18 



41-60 



41-55 



41-50 



II. 



17.6.86 



65 



44-46 



+ 2-62 



46-23 



43-71 



42-40 



42-00 



III. 



5.8.86 



49 



47-12 



+ 2-66 



49-75 



45-98 



44-15 



43-27 



IV. 



24.9.86 



50 



48-94 



+ 1-82 



51-64 



48-43 



45-06 



44-30 



V. 



12.11.86 



49 



49-34 



+ 0-40 



50-50 



49-87 



46-86 



46-10 



VI. 



22.12.86 



40 



47-05 



- 2-29 



46-35 



47-38 



47-86 



47-90 



VII. 



8.2.87 



48 



45-11 



-1-94 



43-60 



45-70 



46-90 



47-32 



VIII. 



25.3.87 



45 



43-80 



-1-31 



43-45 



44-13 



44-00 



43-95 



IX. 



7.5.87 



43 



44-94 



+ 1-14 



46-03 



44-20 



43-97 



43-92 



X. 



14.6.87 



38 



47-34 



+ 2-40 



49-62 



45-99 



45-05 



45-00 



XI. 



7.8.87 



54 



52-34 



+ 5-00 



56-00 



51-52 



47-30 



45-92 



XII. 



29.9.87 



53 



51-74 



-0-60 



53-52 



51-49 



49-21 



48-11 



XIII. 



30.11.87 



62 



4S-60 



-3-14 



47-35 



49-39 



49-85 



49-60 



XIV. 



9.2.88 



71 



45-70 



-2-90 



45-35 



45-90 



46-05 



46-15 



XV. 



1.3.88 



21 



44-10 



-1-60 



44-19 



44-05 



44-00 



44-03 



XVI. 



28.3.88 



27 



43-42 



-0-68 



43-33 



43-50 



43-50 



43-48 



XVII. 



3.9.88 



... 



50-05 





53-34 



49-10 



45-95 



44-10 



These curves of temperature at different depths present much similarity to those of Loch 

 Fyne (fig. 41, Plate XXX.). The air-curve is practically the same, though the maxima for 

 188G and 1888 are rather higher than for Loch Fyne. The curve of mean temperature of 



