CONTENTS. 



NOTICES AND ABSTRACTS 



OF 



MISCELLANEOUS COMMUNICATIONS TO THE SECTIONS. 



MATHEMATICS AND PHYSICS. 



Mathematics. 



Page 



Mr. J. T. Graves on the Polyhedron of Forces 



. — — on the Congruence nx:==n+l (mod p) 



Mr. H. M. Jeffery's Two Memoirs. —I. On a Theorem in Combinations. 



n. On a particular Class of Congi-uences 



Professor Stevelly on a New Method of Treating the Doctrine of Parallel ^ 



Lines ' ' ' 



Mr. H. R. Twining's Models to iUustrate a New Method of teaching ^ 



Perspective 



Light, Heat, Electricity, Magnetism. 



Mr. A. Clatjdet on various Phsenomena of Refraction through Semi-Lenses 



producing Anomalies in the Illusion of Stereoscopic Images « 



Dr. J. H. Gladstone on some Dichromatic Phsenomena among Solutions, and 



the means of representing them 



Mr. W. R. Grove on the Stratified Appearance of the Electrical Discharge. . 10 



Sir W. S. Harris on the Law of Electrical and Magnetic Force 11 



Mr. J. C. Maxwell on the Unequal Sensibility of the Foramen Centrale to 



Light of different Colours ^^ 



on a Method of Drawing the Theoretical Forms of Faraday's 



Lines of Force without Calculation 1" 



on the Theory of Compound Coloui's with reference to 



Mixtures of Blue and YeUow Light 12 



Mr. James Nasmyth on the Foi-m of Lightning 14 



Rev. Baden Powell on Fresnel's Formulae for Reflected and Refracted 



Light ^^ 



Mr. W. Symons on a Modification of the Maynooth Cast Iron Battery 16 



Professor William Thomson on Bellman's Method of observing Atmospheric 



Electricity ; • • 1' 



Mr. E. Vivian on Printing Photographs, with suggestions for introducing 



Clouds and Artistic Efiects 1° 



Mr. WiLDMAN Whitehouse on the Construction and Use of an Instrument 



for determining the Value of Intermittent or Alternating Electric Currents 



for piirposes of Practical Telegraphy 1^ 



_— on the Law of the Squares— is it applicable or not 



to the Transmission of Signals in Submarine Circuits ? 21 



