CONTENTS OF N 53. New Series. 



XLIX. On the Impediments to the Study of Natural History; 

 illustrated by a Reference to certain technical and incidental Ob- 

 scurities, in the Arrangement of the Diurnal Family of Lepidopterous 

 Insects by various celebrated Naturalists. By A CORRESPON- 

 DENT page 321 



L. On the recent Change of Form of the Summit of Mont Blanc. 

 By A CORRESPONDENT 328 



LI. Notice of the Discovery of the Plesiosaurus in Ireland. By 

 JAMES BRYCE, Jun. A.B 331 



LII. On the Tides on the Coast of Great Britain. By J. W. LUB- 

 BOCK, Esq. F.R.S. (With a Map) 333 



LIII. On the Reduction of the North Polar Distances of Stars 

 observed at Greenwich, and corrected by Bradley's Refractions, to 

 Distances according with Ivory's Refractions. By W. GALBRAITH, 

 Esq. A.M 335 



LEV. On the Effect of a Change of Polar Distance on the Re- 

 duction to the Meridian of a Zenith Distance observed out of the 

 Meridian. By A CORRESPONDENT 338 



LV. Observations relative to the Origin and History of the Bush- 

 men. By ANDREW SMITH, M.D. M.W.S., &c. (To be continued). . 339 



LVI. Notices respecting New Books : Phillips's Illustrations of 

 the Geology of Yorkshire 342 



LVII. Proceedings of Learned Societies : Royal Society ; As- 

 tronomical Society ; Linnaan Society ; Zoological Society ; Geo- 

 logical Society ; Friday Evening Proceedings of the Royal Institu- 

 tion of Great Britain ; Cambridge Philosophical Society 354-384 



LVIII. Intelligence and Miscellaneous Articles: Fall of the 

 Broughton Suspension Bridge, near Manchester ; Cambridge Uni- 

 versity ; Manganese in Human Blood ; On Sulfo-Sinapisine, origi- 

 nally termed Sulfo-Sinapic Acid ; Emission of Light during the Com- 

 pression of Gases ; Action of Chloride of Bromine upon Water and 

 ^Ether ; Crystallization of Bismuth ; Re-action of Persalts of Iron 

 and Carbonates ; Inflammation of Phosphorus by Charcoal ; Obser- 

 vations on Aurorae Boreales witnessed at Bedford, at various times, 

 from April 19, 1830, to January 11, 1831, by W. H. White, 

 H.M.C.S.; Rev. W. D. Conybeare's Preliminary Addresses to the 

 Course of Lectures on Theology, delivered at the Collegiate Insti- 

 tution of Bristol ; Dr. Webster's Dictionary j Lunar Rainbows ; Lu- 

 nar Occultations of Planets and Fixed Stars by the Moon in May 

 1831 ; Meteorological Observations for March 1831, Table, &c. 384-400 



It is requested that all Communications for this Work may be addressed, 

 post paid, to the Care of Mr. R. Taylor, Printing Office, Red Lion Court, 

 Fleet Street, London ; where complete Sets of the Old Series of the Phi- 

 losophical Magazine may be had at half of the original price. 



