CONTENTS. 
XX. Letter from Captain Basil Hall, R. N. to Captain Kater, 
communicating the details of experiments made by him and Mr. 
Henry Foster, with an Invariable Pendulum ; in London ; at 
the Galapagos Islands in the Pacific Ocean , near the Equator ; 
at San Bias de California on the N. W. Coast of Mexico ; and 
at Rio de Janeiro in Brazil. With an Appendix, containing 
the Second Series of Experiments in London, on the Return. 
p. 211 
XXL Second Part of the paper on the Nerves of the Orbit. By 
Charles Bell, Esq. Communicated by Sir Humphry Davy, 
Bart. Pres. R. S. p. 289 
XXII. An Account of Experiments made with an Invariable 
Peiidulum at New South Wales, by Major-General Sir Tho- 
mas Brisbane, K. C. B. F. R. S. Communicated by Captain 
Henry Kater, F. R. S. in a Letter to Sir Humphry Davy, 
Bart. Pres. R. S. p. 308 
XXIII. Observations and Experiments on the daily variation of 
the Horizontal and Dipping Needles under a reduced directive 
power. By Peter Barlow, Esq. F. R. S. of the Royal Military 
Academy. Communicated by Davies Gilbert, Esq. V.P.R.S. 
x p. 326 
XXIV. On the Diurnal Deviations of the Horizontal Needle 
when under the influence of Magnets. By Samuel Hunter 
Christie, Esq. M. A. Fellow of the Cambridge Philosophical 
Society : of the Royal Military Academy. Communicated by 
Sir Humphry Davy, Bart. Pres . R. S. p. 342 
XXV. On Fossil Shells. By Lewis Weston Dillwyn, Esq. 
F.R. S. In a Letter addressed to the Right Honourable Sir 
Humphry Davy, Bart. Pres. R. S. p. 393 
