CONTENTS 
OF 
No. XII. 
Page- 
Art. I. History of the Invention of Pendulum Clocks by Chris- 
tian Huygens. By J. H. Van SwiNDEN, Councillor 
of State, Prof, of Nat. Philosophy at Amsterdam, &c. I 97 
II. Observations on the Countries of Congo and Loango, 
^ as in 1790- By Mr Maxwell, Author of Letters to 
Mungo Park, &c. (Concluded from Vol. VI. p. 62.) 213 
III. Account of Electro-Magnetic Experiments made by 
MM. Van Seek, Prof. Van Rees of Liege, and Prof. 
Moll of Utrecht. In a Letter to Dr Brewster, 220 
IV. Barometrical Observations made at the Fall of the 
Staubbach, by J. F. W. Herschel, Esq. F. R. S. L. 
& E., and Charles Babbage, Esq. F. R. S. L. & E. 224 
V. On the Determination of certain Secondary Faces in 
Crystals, which require neither Measurement nor 
Calculation. By A. Levy, M. A. of the University 
of Paris. Communicated by the Author, - 227 
VI. On the Effects of Magnetism on Chronometers. By 
Peter Lecount, Esq. In a Letter to Dr Brewster, 238 
^HI. Extracts from Dr Hibbert’s Description of the Shet- 
land Islands, — 
1. Account of the Pursuit and Capture of a drove of Whales, 240 
2. Account of the Ling Fishery at the Haaf, - 243 
3. Account of the Isle of Stennes, the Holes of Scraada, and 
Grind of the Navir, - - - 247 
4. Account of the Religious Paroxysms of the Shetlanders, 250 
5. Account of the Teutonic Fortress, called the Burgh of 
Mousa, - , - 251 
6. Method of Bloodletting in Shetland, - 255 
VIII. On the Ancient History of Leguminous Fruits. By 
Professor Link. (Concluded from Vol. V. p. 131.) 256 
IX. On the Extraordinary Darkness that was observed in 
some parts of the United States and Canada, in the 
month of November 1819. By Frederick Hall, 
Professor of Mathematics and Natural Philosophy in 
Middlebury College, Vermont, - - 266 
