vi CONTENTS. 
VILL. On the Advantages to be derwed from the Use of Metallic Reflectors for 
Sextants and other Reflecting Instruments ; and on Methods of directly 
determining the Errors in Mirrors and Sun-Shades used in Reflecting 
Instruments. By Joun Aviz, Esgq., 
IX. On the Balance Magnetometer, and its Temperature Correction. By 
J. A. Broun, Esq. Communicated by Sir T. M. BrisBaAng, Bart., 
X. On Wotzasron’s Argument from the Limitation of the Atmosphere, as 
to the Finite Divisibility of Matter. By Grorcr Witson, M.D., 
Lecturer on Chemistry, : : : 
PART II. 
XI. On the Sums of the Digits of Numbers. By the Right Reverend 
Bishop TERROT, ; : ; 
XII. Results of the Makerstoun Observations, No. I. On the Relation of the 
Variations of the Horizontal Intensity of the Earth’s Magnetism to 
the Solar and Lunar Periods. (With Two Plates.) By J. A. Broun, 
Esq. Communicated by Sir T. M. Brispang, Bart., ° 
XIII. On the Decomposition and Dispersion of Light within Solid and Fluid 
Bodies. (With a Plate.) By Sir Davin Brewster, K.H., D.C.L., 
F.R.S., and V.P.R.S., Edin., ; 
XIV. On the Constitution and Properties of Picoline, a new Organic Base 
from Coal-Tar. By Tuomas ANDERSON, M.D., 
XV. Results of the Makerstoun Observations, No. II. On the Relation of the 
Variations of the Vertical Component of the Karth’s Magnetic In- 
tensity to the Solar and Lunar Periods. (With a Plate.) By J. 
ALLAN Brown, Esq., Director of General Sir T. M. BRISBANE’s 
Magnetical and Meteorological Observatory. Communicated by 
Sir T. M. BrisBane, Bart., 
XVI. On the Solubility of Fluoride of Calcium in Water, and its relation to 
the occurrence of Fluoride in Minerals, and in Recent and Fossil 
Plants and Ammals. By GEorcE Witson, M.D., 
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