of Edinburgh, Session 1884-85. 
49 
south-westerly breeze rising to a gale, which increased towards 
evening, prevented water samples being obtained at Stations IX., 
VIII., and VII. returning. This trip showed that the density of 
the water samples decreased steadily, gradually, and uniformly from 
the May to the Oxcar Beacon (V.), hut that the change then be- 
came more rapid, the curve resembling a portion of a rectangular 
hyperbola. The weather for the previous few weeks had been dry 
and warm. 
On October 7, water samples were taken to and from the May 
from 8 a.m. to 7 p.m. The weather was fine but dull, and the sea 
smooth. It was low water at Station VIII. going, and high water 
at Station XI. returning. 
Next day the “ Medusa ” went to Alloa, in rain, slight mist, and a 
north-easterly breeze. Water samples were taken as before. It 
was low water at Inchgarvie (Station V.) going up, and high water 
at the same place returning. 
The water, beautifully clear and transparent, and of a deep green- 
blue colour at the May, became light green and less transparent 
about Inchkeith, and from Inchgarvie onwards it was yellow and 
very muddy. 
The curve for this trip (Plate IV., B) is less regular, but of the 
same general shape as the previous one. 
The November trips were made on the 10th and 11th of the 
month. For the previous week or two there had been high wind 
and much rain, and the rivers had been flooded heavily, but were 
then subsiding. The 10th, when the eastern half of the firth was 
traversed, was bright, clear, and calm. The shortness of daylight 
prevented the yacht from getting further than Station X., at which 
point it was low water. On the 11th it was dull, with a stiff south- 
easterly breeze. It was high water at Station VI. going up, and low 
water at Station V. coming down. The river was greatly flooded, 
and the curve (Plate IV., C) is irregular, and much more abrupt than 
the others. The reading of the density at Station IV. going up 
seems too low, but there is no reason to suspect its accuracy. The 
influence of the flooded streams may be traced by a lowering of 
density down to Station IX. The effect of this “ spate ” was to 
reduce the density at Inchgarvie from 1 ’02382 to 1 '02029, that at 
the Oxcar Beacon from the mean of 1 '02438 to 1 '02022, that at 
VOL. XIII.. 
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