366 Proceedings of the Royal Physical Society. 
Wednesday, March 28, 1866. — William Turner, M B., President, in 
the Chair. 
The following Donations to the Library were laid on the Table, and 
thanks voted to the Donors : — 
1. Proceedings of the Royal Society. Nos. 78, 79, 80. — From the 
Society. 2, The Conservatory Journal, Boston, 1859. Nos. 1, 3, 4. 
3. Board of Science, Second Annual Report, 1859-60. Victoria. — From 
The Colonial Government. 4. Quarterly Journal, Geological Society. 
13 Numbers. — From Professor Balfour. 
The Ray Society's Works were also laid on the table : — (1.) Reptiles 
of British India, by Dr Giinther. 1864. (2.) The British Hemiptera. 
Vol I., Hemiptera — Heteroptera, by John William Douglas and John 
Scott. 
The following Communications were read :— 
I. (1.) Notes on certain Spiral Forms. By William Stevenson, Esq., 
Dunse. Communicated by George Logan, Esq., W.S. 
Every one walking by the side of a flooded river, must 
have observed the cup-shaped depressions formed by the 
eddying of the current. Wherever the stream meets with an 
obstacle on either side, a portion of it is deflected back, and 
whirls round, until it comes in contact with the main cur- 
rent, when it is again deflected, producing one of the de- 
pressions referred to. These, it will be observed, are not 
strictly circular in horizontal section, but spiral. It will be 
further observed, that on the right bank of the stream the 
spiral motion is from left to right, or similar to that of the 
hands of a watch, whilst on the left bank the motion is from 
right to left. The cause of this is sufiiciently obvious. 
On examining the gravel thrown down by flooded streams, 
it will further be observed that these deposits, which appear 
to a casual -observer to be about the most confused and 
irregular things in nature, actually show a beautiful spiral 
arrangement — the turns of the spirals being from left to 
right on the right bank, and vice versa on the left, — these 
spirals also being generally of an elliptical form, the major 
axis pointing up and down stream. 
When a cartload of stones is emptied at once in a heap, 
even in this case the spiral arrangement is distinctly seen — 
the stones being arranged in right or left hand spirals, 
