CONTENTS. 



Art. I. Fifth Letter by Professor James Forbes on 

 Glaciers. Addressed to the Right Honour- 

 able Earl of Cathcart. Communicated by the 

 Author, . . . . . Page 217 



II. On the Comparative Value of different kinds 

 of Parrot, or Candle Coal, for yielding 

 Gas, and on the Illuminating Powers of Gas 

 at different distances from the Manufactory. 

 By Andrew Fyfe, M. D., F. R. S. K, 

 F.R.S.S.A. Communicated by the Royal 

 Scottish Society of Arts, . . . 223 



III. On the Production of Flames in Volcanoes, 



and the consequences that may be drawn 

 therefrom. By M. Leopold Pilla, . 231 



IV. Dependence of the Geographical Relations of 



Countries and Nations on the extent and 

 situation of Forests, . . . 236 



V. Suggestions for the better Ventilation of Sail- 

 ing and Steam- Vessels. By Robert 

 Ritchie, Esq., F.R.S.S.A., &c., Civil-En- 

 gineer, Edinburgh. Communicated by the 

 Royal Scottish Society of Arts. Concluded 

 from page 182, . . . . 261 



VI. Contributions towards establishing the Gene- 

 ral Character of the Fossil Plants of the 

 genus Sigillaria. By William King, Esq., 

 Curator of the Museum of the Natural His- 

 tory Society of Northumberland, Durham, 

 and Xewcastle-upon-Tyne. With two Plates. 

 Communicated by the Author. Continued 

 from page 21, . . . . 272 



