CONTENTS. 



NOTICES AND ABSTRACTS OF MISCELLANEOUS 

 COMMUNICATIONS TO THE SECTIONS. 



MATHEMATICS AND PHYSICS. 



Page 



Mr. Charles Graves on a General Geometric Method I 



Sir W. R. Hamilton on the Propagation of Light in vacuo 2 



Sir W. R. Hamilton on the Propagation of Light in Crystals 6 



Professor Powell on some Points connected with the Theory of Light .... 6 

 Sir D. Brewster on an Ocular Parallax in Vision, and on the Law of Vi- 

 sible Direction 7 



Sir D. Brewster on a New Phenomenon of Colour in certain specimens 



of Fkior Spar 10 



Sir D. Brewster's Account of certain New Phenomena of Diffraction .... 12 

 Sir D. Brewster's Account of an Analogous Series of New Phenomena of 



Diffraction when produced by a Transparent Diffracting Body 12 



Sir D. Brewster on the Combined Action of Grooved Metallic and Trans- 

 parent Surfaces upon Light 13 



Sir D. Brewster on a new kind of Polarity in Homogeneous Light 13 



Sir D. Brewster on some Preparations of the Eye by Mr. Clay Wallace, 



of New York 14 



Sir J. F. W. Herschel on the Structure of the Vitreous Humour of the 



Eye of a Shark 15 



Professor Wheatstone on Binocular Vision ; and on the Stereoscope, an 



instrument for illustrating its phenomena 16 



Sir John F. W. Herschel's Observations on Stars and Nebulse at the Cape 



of Good Hope 17 



Sir John F. W. Herschel on Halley's Comet 19 



Sir Thomas M. Brisbane on the Difference of Longitude between London 



and Edinburgh 20 



Mr. G. B. Airy on the means adopted for correcting the Local Magnetic 



Action of the Compass in Iron Steam-ships ^ 21 



Lieut.-Colonel Reid's Statement of the Progress made towards developing 

 the Law of Storms ; and of what seems further desirable to be done, to 



advance our knowledge of the subject 21 



Professor A. D. Bache's Note on the Effect of Deflected Currents of Air 



on the Quantity of Rain collected by a Rain-gauge 25 



Dr. William Smith on the Variations in the Quantity of Rain which falls 



in different Parts of the Earth 27 



Professor Forbes's Notice of a Brine Spring emitting Carbonic Acid Gas.. 28 



Dr. Daobeny on the Climate of North America 29 



Rev. J. Watson on the Helm Wind of Crossfell 33 



Mr.HoDGKiNsoN on the Temperatures observed in certain Mines in Cheshire 34 

 Mr. Dent's Facts relating to the Effects of Temperature on the Regulators 

 of Time-keepers ; and description of some recent improvements in Pen- 

 dulums, with Observations, and Tabulated Experiments 35 



Sir John Robison's Notice of a cheap and portable Barometrical Instru- 

 ment proposed for the use of Travellers in Mountainous Districts 37 



The Rev. Professor Temple Chevallier's Tables intended to facilitate the 



computation of Heights by the Barometer 38 



a2 



