vi CONTENTS. 



PAGE 



VIII. On the Advantages to be derived from the Use of Metallic Reflectors for 

 Sextants and other Reflecting Instruments; and on Methods of directly 

 determininq the Errors in Mhtors and Sun-Shades used in Reflecting 

 Instruments. By John Adie, Esq., t>l 



IX. On the Balance Magnetometer, and its Temperature Correction. By 



J. A. Begun, Esq. Communicated by Sir T. M. Brisbane, Bart., 67 



X. On WoLLASTox''s Argument from the Limitation of the Atmosphere, as 

 to the Finite Divisibility of Matter. By George Wilson, M.D., 

 Lecturer on Chemistry, ....... 7!) 



PART II. 



XI. On the Sums of the Digits of Numbers. By the Right Reverend 



Bishop Terkot, 87 



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.) ByJ.A. Broun, 

 Esq. Communicated by Sir T. M. Brisbane, Bart., . '. 99 



XIII. On the Decomposition and Dispersion of Light within Solid and Fluid 



Bodies. (With a Plate.) By Sir David Brewster, K.H., D.C.L., 

 F.R.S., and V.P.R.S., Edin., Ill 



XIV. On the Constitution and Properties of Picoline, a new Organic Base 



from Coal-Tar. By Thomas Anderson, M.D., . . . 123 



XV. Results of the Makerstoun Observations, No. II. On the Relation of the 

 Variations of the Vertical Component of the EartKs Magnetic In- 

 tensity to the Solar and Lunar Periods. (With a Plate.) By J. 

 Allan Broun, Esq., Director of General Sir T. M. Brisbane's 

 Magnetical and Meteorological Observatory. Communicated by 

 Sir T. M. Brisbane, Bart., ....... 137 



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 Animals. By George Wilson, M.D., . . 14.5 



