.i!K 



DR HUGH ROBERT MILL ON THE 



Table XXIX. — Density at 15 0, 56 and Percentage of Sea Water. 



Density at 15°"56. 



Percentage Sea Water. 



Differences. 



1-01300 



50-0 



Density. Percentage. 



1400 



539 



0-00010 0-4 



1500 



577 



20 0-8 



1600 



615 



30 1-1 



1700 



65-4 



40 1-5 



1800 



69-2 



50 19 



1900 



73-1 



60 2-3 



2000 



769 



70 2-6 



2100 



80-8 



80 30 



2200 



84-6 



90 3-4 



2300 



88-5 





2400 



92-3 



0-00003 0-1 



2500 



96-2 



5 0-2 



2600 



ioo-o 



7 0-3 



The most striking fact brought out by Table XXVIII. is the full justification it affords 

 of the term " Sea Area" as applied to the Estuary and Lochs of the Clyde. It is only in 

 the Gareloch and at the very head of Loch Fyne that there is less than 90 per cent, of 

 pure sea water present, the average of all the stations being 93 - 4 per cent. As the 

 stations were most numerous in the freshest parts of the area, this figure is, of course, 

 much under that expressing the true mean salinity of the Area, which must be arrived at 

 by a longer process. 



The normal salinity added in the table is estimated from the assumed normal values 

 given for bottom water in Table XXIV. The assumption is that all the stations in the 

 landward and seaward divisions respectively have their salinity reduced in the same 

 proportion as the normal rainfall is distributed — most at the extremities of the landward 

 divisions. The surface-normals bore to the bottom-normals the same ratio as that actu- 

 ally found in the observations. 



The Amount and Fluctuation of Sea Water in each Division. — Combining the per- 

 centage composition of the water at each station, I have calculated the actual volumes of 

 sea water and river water present in the Area as an average for the period under observa- 

 tion. To do this in the case of a basin such as is represented in section in fig. 1, in which 



the letters A, B, C, D represent the percentage of sea 

 water at the respective stations, and the letters a, b, c 

 the distance in sea-miles separating these stations, the 

 average of percentage A and B is supposed to prevail 

 throughout the a miles separating the stations, the 

 average of B and C throughout the next b miles, and so on. Thus the actual percentage 

 of sea water in the basin, supposing each station to represent the salinity in the cross- 

 section and not only in the centre, is : — 



_ (A+B)q+(B + C)6+(C + D)c 

 2(a+b+c) 



F*. i. 



