of Edinburgh, Session 1884-85. 
347 
9. On Pitchered Insectivorous Plants. Part II. By 
J. M. Macfarlane, D.Sc. 
10. Note on the Salinity of the Tay Estuary and of St 
Andrews Bay. By Hugh Robert Mill, B.Sc., F.C.S. 
In January I read a paper on the salinity of the Firth of Forth,* 
in which the law governing the distribution of salt in that estuary 
was pointed out. It appeared that in the eastern or seaward part 
of the Firth the change in mean salinity per mile was very slight, 
and the tidal range was small, while both decreased gradually as 
the sea was approached. On the other hand, the riverward half of 
the Firth showed a rapid alteration in density along its length, and a 
correspondingly great range between high and low tide. 
The estuary of the Tay is shorter, narrower, and shallower than 
that of the Forth, and the river is much larger, of great volume, 
and more rapid. It might then be expected that the condition of 
the seaward part of the Firth of Tay would resemble that of the 
riverward portion of the Forth in its main characteristics, while the 
sea around the mouth of the estuary would be perceptibly freshened. 
A slight dip in the salinity curve at the Isle of May was referred 
to in the paper cited above,! and the suggestion was thrown out 
that this might be due to the diluting action of the fresh water of 
the Tay. This hypothesis has been confirmed by observations made 
during the first week of June 1885. 
The Scottish Marine Station’s yacht “ Medusa ” went from Granton 
to the Tay on June 2nd, when water samples were collected at 
regular intervals both from the surface and the bottom. These 
were afterwards examined, the density determined as described 
previously, J and reduced to 15°*56 C. to admit of comparison with 
other observations. The result of this day’s work is shown in 
Table I. 
Table I. 
Position, Off Inchkeith. Off Elie. Off Crail. St Andrews Bay. Tay Fairway Buoy. 
Tide, li hr. ehb. 4 hrs. ebb. 1. w. 1 hr. fid. If hr. flood. 
Surface i X-Q2488 1-02547 1-02537 1-02505 1-02435 
density, J 
* Proc. Roy. Soc. Edin . , xiii. pp 29-64. t Ibid., p. 53. 
+ Ibid., p. 35. 
2 A 
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