VI 
CONTENTS. 
VIII. An Account of the urinary organs and urine of two species 
of the genus Rana. By John Davy, M. D . F. R. S . p. 95 
IX. An account of a Micrometer made of Rock Crystal. By 
G. Dollond, F. R. S. p. 101 
X. The Bakerian Lecture. On the best kind of steel and form for 
a compass needle. By Capt. Henry Kater, F. R. S. p. 104 
XI. Notice respecting a volcanic appearance in the Moon , in a 
Letter addressed to Sir Humphry Davy, Bart , P. R. S. By 
Captain Henry Kater, F. R. S. p. 130 
XII. A farther account of fossil bones discovered in caverns 
inclosed in the lime stone rocks at Plymouth. By Joseph 
Whidbey, Esq. In a Letter addressed to Sir Everard 
Home, Bart. V. P. R. S. p. 133 
XIII. On the aeriform compounds of Charcoal and Hydrogen ; 
with an account of some additional experiments on the gases 
from oil and from coal. By William Henry, M. D. 
F. R. S. &c. p. 13 6 
APPENDIX. 
Meteorological Journal for 1820, kept at the Apartments of the 
Royal Society. 
