CONTENTS. 



NOTICES AND ABSTRACTS 



MISCELLANEOUS COMMUNICATIONS TO THE SECTIONS. 



I 



MATHEMATICS AND PHYSICS. 



Mathematics. 



Page 



Mr. Arthur Cayley on the Porism of the in-and-eircumscribed Triangle ... 1 



Mr. M. Collins on the possible and impossible cases of Quadratic Duplicate 



Equalities in the Diophantine Analysis 2 



Mr. A. J. Ellis on a more general Theory of Analytical Geometry, including 



the Cartesian as a particular case 5 



Sir W. R. Hamilton on the conception of the Anharmonic Quaternion, and 



on its application to the Theory of Involution in Space 7 



Light, Heat, Electricity, Magnetism. 



Dr. Adamson on the Fixing of Photographs 7 



Sir David Brewster on the Triple Spectrum 7 



on the Binocular Vision of Surfaces of Different Colours 9 



on the Existence of Acari in Mica 9 



on the Absorption of Matter by the Surfaces of Bodies 9 



on the Remains of Plants in Calcareous Spar from 



King's County, Ireland 9 



on the Phaenomena of Decomposed Glass 10 



Mr. Paul Cameron on the Making and Magnetizing of Steel Magnets 10 



on the Deviations of the Compass in Iron Ships and the 



means of adjusting them 10 



Professor Chevallier on an Analogy between Heat and Electricity 10 



M. Antoine Claudet on the Polystereopticon 10 



M. Leon Foucault on the Heat produced by the Influence of the Magnet 



upon Bodies in Motion 11 



Dr. Green on a Machine for Polishing Specula 11 



M. W. Haidinger on the Optical Properties of Cadmacetite 11 



Mr. Evan Hopkins on the Optical Illusions of the Atmospheric Lens 12 



Mr. J. P. Joule's Account of some Experiments with a large Electro-Magnet 12 



M. Nachot on New Forms of Microscope, adapted for Physiological Demon- 

 stration 12 



Dr. William Scoresby's Elucidations, by Facts and Experiments, of the 



Magnetism of Iron Ships, and its changes 12 



Professor Stokes on the Achromatism of a Double Object-Glass 14 



