vi CONTENTS. 



Page. 



Sir John F. W. Herschel on the Absorption of Light by coloured 

 Media, viewed in connexion with the undulatory Theory .... 373 



Tlie Rev. Baden Powell on the Dispersive Powers of the Media 

 of the Eye, in connexion with its Achromatism 374 



R. Potter, Jun., on the power of Glass of Antimony to reflect 

 Light 377 



on a Phaenomenon in the Interference of Light 



hitherto undescribed _ 378 



Sir John F. W. Herschel's Explanation of the Principle and Con- 

 struction of the Actinometer 379 



M. Melloni's Account of some recent Experiments on Radiant 

 Heat 381 



John Prideaux on Thermo-Electricity 384 



W. Snow Harris on some new Phsenomena of Electrical Attrac- 

 tion 386 



The Rev. John G. MacVicar on Electricity 390 



The Rev. J. Power's Inquiry into the Cause of Endosmose and 

 Exosmose 391 



Michael Faraday on Electro -chemical Decomposition 393 



Dr. Turner's Experiments on Atomic Weights 399 



Prof. Johnston's Notice of a Method of analysing Carbonaceous 

 Iron '. 400 



R. Potter, Jun. A Communication respecting an Arch of the 

 Aurora Borealis 401 



John Phillips's Report of Experiments on the Quantities of Rain 

 falling at different Elevations above the Surface of the Ground at 

 York 401 



II. Philosophical Instruments and Mechanical Arts. 



The Rev. Wm. Scoresby on a peculiar Source of Error in Experi- 

 ments with the Dipping Needle 412 



The Rev. W. H. Miller on the Construction of a new Barometer 414 



W. L. Wharton on a Barometer with an enlarged Scale 414 



W. S. Harris on the Construction of a new Wheel Barometer . . 414 



J. Newman on a new Method of constructing a Portable Barometer 417 

 The Rev. James Cumming on an Instrument for measuring the 



total heating Effect of the Sun's Rays for a given time 418 



on some Electro-magnetic Instruments 418 



Andrew Ure on the Thermostat, or Heat-governor 419 



Thomas Davison on a Reflecting Telescope 420 



W. L. Wharton on a Steam-engine for pumping Water 421 



E. J. Dent on the Application of a glass Balance-spring to Chro- 

 nometers 421 



E. HoDGKiNSON on the Effect of Impact on Beams 421 



on the direct tensile Strength of Cast Iron 423 



J. I. Hawkins's Investigation of the Principle of Mr. Saxton's loco- 

 motive differential Pulley, &c 424 



John Taylor's Account of the Depths of Mines 427 



J. Owen on Naval Architecture 430 



