CONTENTS 
OF 
No. XXI 
Page 
Art. I. Observations on Electrical Theories. By John Leslie, 
Esq. Professor of Natural Philosophy in the Univer- 
sity of Edinburgh, and Corresponding Member ol 
' the Royal Institute of France (with a Plate), - 1 
II. Experiments on the Growth of Pearls, with Observa- 
tions on their Structure and Colour. By W. T. 39 
III. Notice in regard to Macquarie Island. By Mr Thomas 
Raine. Communicated by Sir Thomas Brisbane, 
Bart., &c. - 4b 
IV. On the Formation of Dew. By Henry Home Black- 
adder, Esq. Staff Assistant-Surgeon, - 51 
V. A popular View of Mr Barlow’s Magnetical Experi- 
ments and Discoveries, particularly as they have 
been rendered applicable to the Correction of the Lo- 
cal Attraction of Vessels (with a Plate), - 65 
VI. Analysis of Pinite from St Pardoux in Auvergne. By 
C. G. Gmelin, M. D. of Tubingen. Communicated 
by the Author, - - = 87 
VII. On the Geognostical Phenomena at the Temple of Se« 
rapis (with an Engraving), - - 91 
VIII. Experiments on the Application of Professor Dcebe- 
reiner’s recent Discovery to Eudiometry. By Ed- 
ward Turner, M. D. Fellow of the Royal College of 
Physicians, and Lecturer on Chemistry, Edinburgh. 
Communicated by the Author, 99 
IX. Notice of the Colossal Ray or Skate; with an Account 
of the Capture of one, at Port Royal, Jamaica, where 
it is known under the name of Sea-Devil. By A. 
Lamont, Esq. Lieutenant 91 §t Regiment, - ilf 
