IV CONTENTS. 



Page 



Meteorological Observations made by Mr. Thompson at the 

 Garden of the Horticultural Society at Chiswick, near 

 London; by Mr. R. Hocking at Penzance, and Mr.Veall at 

 Boston 80 



NUMBER XX.— FEBRUARY. 



Mr. R. W. Fox's Notice of an Instrument for ascertaining va- 

 rious Properties of Terrestrial Magnetism, and affording a 

 permanent Standard Measure of its Intensity in every Lati- 

 tude 81 



Mr. S. Earnshaw's Remarks on Prof. Moseley's "Principle of 

 Least Pressure " 89 



Messrs. F. and E. Rodgers on certain Metallic Cyanurets. ... 91 



Mr. W.J. Henwood on some Meteorological Phenomena ob- 

 served in the Mount's Bay, Cornwall 103 



Rev. W. Ritchie on the Mode of detonating a Mixture of 

 Oxygen and Hydrogen by a Spark induced by a small horse- 

 shoe Magnet 104- 



Mr. T. Graham's Reply to Mr. R. Phillips's Observations on 

 the Use of Chemical Symbols 106 



Mr. C. T. Beke on the former Extent of the Persian Gulf, and 

 on the comparatively recent Union of the Tigris and Eu- 

 phrates 107 



Facts relating to Optical Science. No. I. Communicated by 

 Mr. II. F.Talbot .-.•••■• 112 



Sir David Brewster's Observations on the supposed Vision of 

 the Blood-vessels of the Eye 115 



Mr. J. Curtis's Descriptions of some nondescript British Species 

 of Mayflies of Anglers 120 



Proceedings of the Royal Society 125 



; Geological Society 147 



: Linnaean Society 150 



_ - — Marylebone Literary and Scientific Insti- 

 tution 151 



Test for Hydrocyanic or Prussic Acid, and Method of appre- 

 ciating the Quantity 151 



Oxalate of Chrome aivl Potash and Protosulphate of Iron and 

 Magnesia — New Aci 1 in Nux Vomica 158 



On Cusparia from Angustura Bark 151 



Separation of Osmium and Iridium — Action of Bisulphate of 

 Potash and Chloride of Potassium on certain Metals — Per- 

 mani;anesiate of Potash 155 



Spark during the Freezing of Water by /Ether — Separation of 



Barytes and Strontia — Composition of Serum — Serolin. . . . 156 

 Royal Observatory of Ourle — Mr. R. I. Murchison on the 

 Freshwater Limestone between the Seams of Coal in the 

 Neighbourhood of Shrewsbury 158 



