CONTENTS. 
ii 
Art. XL On the proper Method of laying down a Ship’s Track 
on Sea Charts^ with some Remarks on the Import- 
ance of Time-keepers in Navigation. By Captain 
Basil Hall^ R. N. F. R. S. Lond. & Edin. 277 
XII. Account of a new Arrangement of the Algae. By H. 
Christ. Lyngbye^ - - 282 
XIII. A Method of determining the Height of Cliffs or 
Mountains^ by measuring the Depression of the Ho- 
rizon. By William ScoRESBY, Esq. yzw. F. R. S. E. 288 
XIV. Account of a Visit made to the Baths of St Filippo in 
Tuscany^ with a Description of the Mode of forming 
Stone Medallions in Basso Relievo from the Waters 
of the Spring. In a Letter from Dr Gosse of Ge- 
neva, to Professor Jameson, - 290 
XV. An Account of Several Shocks of Earthquakes and 
other Remarkable Phenomena, which occurred in 
South Carolina previous to the Destruction of La- 
guira and Caraccas, and the Eruption of the Soufriere. 
By Mr Tartt. Communicated by the Author, 300 
XVI. Account of the Mine or Quarry of Corundum in Sin- 
graula. By Francis Hamilton, M. D.F. R. S. & 
F. A. S. Lond. & Edin., - - 305 
XVII. Account of Rocks formed by Hot-Springs, Torrents 
of Hot Water, bursting of Subterranean Lakes, Air- 
Volcanoes, and Cold-Springs. By Professor Jame- 
son, - - - 307 
XVIII. Description and Use of a Table for Correcting the ob- 
served Altitude of the Sun’s Lower Limb. By Mr 
W. Galbraith. In a Letter to Dr Brewster, 3I6 
XIX. Results of Captain Rater’s Experiments for determin- 
ing the Length of the Pendulum, at the principal 
Stations of the Trigonometrical Survey, - 19 
XX. On the Discovery of Potash in Sea Water. In a Let- 
ter from Dr Wollaston to Dr Marcet, 325 
XXL Short Comparison of the Volcanic Rocks of France 
with those of a similar nature found in Scotland. In 
■ a Letter addressed to Professor Jameson, by Ami 
Boue', M. D. M. W. S., - - 326 
XXII. On the Optical Properties and Mechanical Condition 
of Amber. By David Brewster, LL. D. F. R. S. 
LoniJ. & Edin., &c. - - 332 
