NUMBER LXXXIX.— APRIL. 



Rev. Prof. Sedgwick and Mr. Roderick Impey Murchison's 

 Classification of the Older Stratified Rocks of Devonshire and 

 Cornwall 24 1 



Mr. J. O. Halliwell on a very particular and curious Account 



. of the Comet of 1472, from a contemporary MS. Chronicle 

 in Peterhouse Library 260 



Rev. B. Powell's Observations on some points in the Theory of 

 the Dispersion of Light 261 



Mr. J. Maclean's Meteorological Observations made during 

 Voyages in the Atlantic and South Pacific Oceans ; and Alti- 

 tudes in the Vicinity of Lima measured by the Sympieso- 

 meter 268 



Mr. Ivory (The Bakerian Lecture) on the Theory of the 

 Astronomical Refractions 376 



CONTENTS. V 



Page 

 Rev. J. Grooby on the Passage of the Moon across the Pleiades 



in March, August, September, and November, 1839 177 



Col. R. Wright's Meteorological Observations during a Resi- 

 dence in Colombia between the Years 1820 and 1830 .... 179 

 Mr. T. Webster's Letter to Professor Forbes on his Communi- 

 cation on the Colour of Steam in the Philosophical Maga- 

 zine of February 1839 184 



Mr. J. T. Cooper's Remarks on Hydrocyanic Acid 186 



Prof. J. J. Sylvester on the Motion and Rest of rigid Bodies. . 188 



Sir D. Brewster on the Colours of Mixed Plates 191 



Mr. H. F. Talbot's Account of the Art of Photogenic Drawing 196 

 Proceedings of the Royal Society, Geological Society, and 

 Astronomical Society ; Friday-Evening Meetings at the Royal 



Institution 21 1—230 



On the Chloro-chromic Acid of Dr. Thomson 230 / 



Fall of Meteorites in South Africa 230^ t 



Alloxan 231 / 



Alloxanic Acid 232 '' 



AUoxanic Acid and Metallic Oxides 233 



Mesoxalic Acid 233 



Mykomelinic Acid 234 



Parabanic Acid 234 



Oxaluric Acid 235 



Oxaluric Acid and Metallic Oxides 235 



Pneumatic Telegraph 236 



Method of distinguishing Trap from Basalt 237 



Absorption of Azote by Plants during Vegetation 237 



Exploration of the Indian Archipelago 238 



On the Influence of Native Magnesia on the Germination and 



Fructification of Vegetables, by Angelo Abbene 238 



Meteorological Observations for January 1839 239 



Table 240 



