108 Proceedings of the Royal Society 
The other Section lies to the westward of Kincraig, and runs 
nearly at right angles to the former, passing from the shore inland 
up the course of the Cockle Mill Burn. It shows the following beds: — 
1. Blown sand rising into dunes close to the shore. 
2. The so called raised beach consisting of sand, shingle, and 
shells in layers, the shells being the common species of the shore, 
and very much in the same state as those now on the beach. This 
deposit is powerfully displayed, rising at some points to twenty 
feet above high-water mark. 
3. Further inland, and apparently underlying No. 2, is a series 
of sands and clays in contorted layers. Marine shells occur at 
various points. One of the layers of clay was pointed out contain- 
ing numerous specimens of Scrobicularia piperata in their natural 
position, with the siphonal end uppermost. As this bed is from 
twelve to fourteen feet above high-water mark, attention was called 
to the evidence thus furnished for a rise in the bed of the Firth, 
and its remarkable coincidence with the evidence furnished by the 
same deposits at Stirling and Portobello. 
4. The submerged forest of Largo Bay as it is found near the 
mouth of the stream, between tide-marks. 
The additional species of shells were described as determined by 
Dr 0. Tozell, and the still more complete evidence thus furnished 
of extreme arctic cold. 
2. On the Motions and Colours upon Films of Alcohol, 
Volatile Oils, and other Fluids. By Sir David Brewster, 
K.H., F.B.S., &c. 
In a paper “ On the Phenomena of thin Plates exposed to 
Polarised Light,” published in the Philosophical Transactions for 
1841, the author observed certain motions and colours upon some 
of the volatile and fixed oils, the cause of which he did not attempt 
to discover. Their apparent similarity to the molecular move- 
ments and colours, described in a preceding paper, induced him to 
resume the subject. 
When a drop of alcohol is placed upon an aperture the fifth of 
an inch in diameter or less, a concave lens will be formed upon it. 
As the alcohol evaporates, a very small plane film will appear in 
the centre, and will gradually increase till it fills the aperture. If 
