of Edinburgh, Session 1884 - 85 . 
59 
A probable explanation of tbe freshness of the quarry surface 
water at times is that the River Almond when in flood, or whether 
wind is in certain directions, dilutes the water along the shore to the 
east of it. This would also account for the water near the quarry 
being denser at low tide, for then the Almond runs into the firth on 
the west of Cramond Island, and so carries its freshening influence 
in another direction (see Plate III.). 
A number of glass floats, coloured distinctively, were thrown 
into the Almond on several occasions just at the turn of the tide, 
immediately after high water, but none of them were seen again, 
though all the boys of the neighbourhood were on the alert along 
the shore, a small reward having been offered for each float found. 
5. The Bottom. Water of the Firth. 
As there was considerable time lost in devising and testing a 
suitable means of collecting samples of bottom water, the number 
of cases for consideration is small. 
It may be generally stated, that the part of the firth east of 
Inchkeith is the region where the difference between the density 
of surface and bottom water is least, and that the difference 
decreases steadily towards the May. Towards Alloa, on the other 
hand, the differences in the density between surface and bottom 
water are great, but they are greatly influenced by the tide. 
Table XII. gives details of 1 9 comparisons between bottom and 
surface water. 
At the Hen and Chickens Buoy, off Grangemouth, the depth is 
only 5J fathoms, but the salinity is very much greater at the 
bottom than at the surface. The difference is least observed at 
low water, but as the flood tide sets in it appears to increase, and 
then to fall off again as the ebb commences. The only divergence 
from this rule noticed was on November 11, when the rivers 
were all much flooded, and the current very rapid. It would appear 
that these observations confirm the theory that sea water ascends 
rivers along the bottom under the opposite current of fresh water. 
At Inchgarvie, where there is a deep depression (over 40 
fathoms) in the middle of the stream, the bottom water is always 
much salter than that at the surface, and the result is most 
noticeable at low water. The difference is usually like that between 
