iv CONTENTS Or VOL. XIII. — FOURTH SERIES. 



Page 

 Mr. D. Forbes's Chemical Examination of, and Remarks on. 



the Mineral Species Tyrite 91 



Prof. Miller on the Anharmonic Ratio of Radii normal to Four 

 Faces of a Crystal in one Zone ; and . on the Change of the 



Axes of a Crystal 96 



Mr. J. Elliot on two new Forms of the Stereoscope, intended 

 for the purpose of uniting Large Binocular Photographic 

 Pictures ; and Mr. G. Waterston on a third Form of the same 



Instrument, for the same purpose 104 



Mr. P. J . Martin on the Anticlinal Line of the London and Hamp- 

 shire Basins (concluded) 109 



The Rev. S. Haughton's Notes on Mineralogy. — No. IV. On 



the Pitchstone Porphyry of Lough Eske, Co. Donegal 116 



Dr. Atkinson's Chemical Notices from Foreign Journals 118 



M. Holzmann on the Vibration of Polarized Light in the Plane 



of Polarization 125 



Proceedings of the Royal Society 129 



Geological Society 145 



On the " Antrimolite " of Thomson, by Dr. Heddle 148 



On the Magnetism and Electric Conductibility of Potassium 



and Sodium, by M. Lamy 148 



On the Movements of the Floating Crystals of some Organic 



Acids, by A. Schefczik 149 



Meteorological Observations for December 1856 151 



Table 152 



NUMBER LXXXV.— MARCH. 



Prof. Draper on the Diffraction Spectrum. — Remarks on M. 



Eisenlohr's recent Experiments 153 



Dr. Day on the Tlieory of Parallels 156 



Prof. Stokes on the Polarization of Diffracted Light 159 



Prof. Wilson on M. J. Nickles' claim to be the discoverer of 



Fluorine in the Blood 162 



Mr. E. Foote on the Heat in the Sun's Rays 167 



Mr. A. Cayley on the Theory of the Analytical Forms called 



Trees 172 



Prof. Sedgwick's Remarks on a passage in the President's Ad- 

 dress delivered at the Anniversary Meeting of the Geological 



Society of London on the 15th of February, 1856 176 



Dr. Atkinson's Chemical Notices from Foreign Journals. ..... \8'3 



The Rev. G. Salmon on the Problem of the In-and circum- 

 scribed Triangle 190 



Mr. C. W. Vincent on certain Double Compounds of Ammonia 



and Chromium 191 



Proceedings of the Royal Society 1 94 



Geological Society 201) 



. Cambridge Philosophical Society '215 



