VI CONTENTS. 



Page 



VI. A Description of a Fossil Tree, discovered in the Quarry of 



Craigleith. near Edinburgh, in the month of November 



1830 ; with a Short Account of a Fragment and Branch 



found in 1831. By HENRY WITHAM, Esq. F. R. S. Ed., 



F. G. S., &c. &c. .... 147 



VII. On the Horary Oscillations of the Barometer near Edinburgh, 

 deduced from 4410 Observations ; with an Inquiry into 

 the Law of Geographical Distribution of the Phenomenon. 

 By JAMES D. FORBES, Esq. F. R. S. E. - - 153 



VIII. On a new Species of Coloured Fringes, produced from re- 

 flexion between the Lenses of Achromatic Compound Ob- 

 ject-Glasses. By DAVID BREWSTER, LL. D., F. R. S., 

 V. P. R. S. Ed., &c. - - 191 



IX. Account of some Experiments in which an Electric Spark was 

 elicited from a Natural Magnet. By JAMES D. FORBES, 

 Esq. F. R. S. Ed., F. G. S., &c. - - - 197 



X. On a New Electrometer, and the Heat excited in Metallic 

 Bodies by a Voltaic Electricity. By WILLIAM SNOW 

 HARRIS, Esq. F. R. S. - ao6 



XL On the Law of the Diffusion of Gases. By THOMAS GRAHAM, 



Esq. M. A., F. R. S. Ed., &c. - 222 



XII. On the Equations of Loci traced upon the Surface of the 

 Sphere, as expressed by Spherical Co-ordinates. By 

 THOMAS STEPHENS DAVIES, Esq. F. R. S. Ed., F.R. A. S. 259 



