VI CONTENTS. 



Page 

 Proceedings at the Friday-Evening Meetings of the Royal 



Institution of Great Britain 309 



■ of the Cambridge Philosophical Society 314? 



Prof. Airy's Account of an Aurora Borealis, seen at Cambridge 



on the 13th of March 315 



Lunar Rainbows— Commemoration of the Centenary of the 



Birth-day of Priestley 317 



Present Work of the Five best Steam-Engines in Cornwall ... . 318 

 Cambridge Meeting of the British Association — Continental 



Association of Philosophers — Occultations of fixed Stars by 



the Moon, in April and May, 1833 319 



Meteorological Observations 320 



NUMBER XI.— MAY. 



Mr. J. S. Enys's Remarks on the Granite found near Penryn, 



and on the Mode of working it 321 



Mr. R. W. Fox's Geological Sketch of a Portion of the Granite 



District near Penryn, referred to in the preceding Paper.. . 326 

 Mr. J. Nixon's Particulars of the Measurement, by various 

 Methods, of the Instrumental Error of the Horizon-Sector 



described in Phil. Mag. vol. lix 327 



Mr. A. Pritchard's Account of Test Objects for Microscopes. . 335 

 Mr. J. Scrymgeour's Narrative of Experiments made with the 

 Seconds Pendulum, principally in order to determine the 

 hitherto unassigned Amount of the Influence of certain mi- 

 nute Forces on its Rate of Motion (continued) 344 



Mr. R. Murphy on the Mathematical Laws of Electrical Influence 350 



Prof. T. Graham on the Laws of the Diffusion of Gases 351 



Mr. H. F. Talbot's Remarks on Chemical Changes of Colour. . 359 

 Sir D. Brewster's Observations on the Absorption of Specific 



Rays, in reference to the Undulatory Theory of Light 360 



Mr. J. Phillips's Modification of the Electrophorus of Volta . . 363 

 Mr. W. Sturgeon on the Theory of Magnetic Electricity (con- 

 tinued) 366 



Prof. W. R. Hamilton's Note on Mr. Potter's Reply 371 



New Books :— Journal of the Asiatic Society of Calcutta 371 



Proceedings of the Royal Society 373 



Linnaean Society 377 



Royal Astronomical Society 378 



Philosophical Society of Cambridge 380 



Commemoration of the Centenary of the Birth of Dr. Priestley 382 



M. Dumas's Experiments on Minium 402 



M. Thenard's Preparation of Peroxide of Hydrogen 403 



Composition of CafFein — Analysis of the Sulpho-Plumbiferous 



Tellurium 404 



Action of Chlorine upon Gum — Mr.B.BevanonCovent-Garden 

 Measures 405 



