ll iti i 
Doubly Refracting Structure of Topaz. 369 
1. On a Possible Explanation of the Adaptation of the Kye to 
Distinct Vision at Different Distances. By Profes- 
sor Forbes. 
2. Notice of an Ancient Beach near Stirling. By Charles 
Maclaren, Esq. 
Monday, 6th January 1845. 
Sir T. M. BRISBANE, Bart., President, in the Chair. 
The following Communications were read :— 
1. Farther Remarks on the Electrical Organs of the Rays. 
By Dr Stark. 
2. Observations on the same subject. By John Goodsir, Esq. 
3. On the Cause which has produced the Present Form 
and Condition of the Earth’s Surface. By Sir George 
Mackenzie, Bart. 
Monday, 20th January 1845. 
The Right Reverend Bishop TERROT, V. P., in the Chair. 
The following Communications were read :— 
1, Some Account of the Magnetic Observatory at Makerstoun, 
and of the Observations made there. By J. A. Broun, 
Esq. Communicated by Sir T. M. Brisbane, Bart. 
2. Description of a Sliding Scale for Facilitating the Use of 
the Moist-bulb Hygrometer. By James Dalmahoy, Esq. 
3. Account of Experiments to Measure the Direct Force of 
the Waves of the Atlantic and German Oceans. By 
Thomas Stevenson. Communicated by David Stevenson, 
Kisq. 
4. A Verbal Communication in regard to Chevalier’s Expe- 
riments on the Decomposition of certain Salts of Lead 
by Charcoal. By Dr Traill. 
Monday, 3d February 1845. 
Sir T. M. BRISBANE, Bart., President, in the Chair. 
The following Communications were read :— 
1. On a Peculiar Modification of the Doubly Refracting 
Structure of Topaz. By Sir D. Brewster, K.H. 
While exaaiining, in polarised light, some of the crystals which 
VOL. XXXVIII. NO. LXXVI.—APRIL 1845, 2A 
