366 Proceedings of the Boy at 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 Worts 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 Spirrtl 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 sufficiently 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, 



