CONTENTS. 



SECTION XXXII. 



Electro-Dynamics Reciprocal Action of Electric Currents Identity of 

 Electro-Dynamic Cylinders and Magnets Differences between the Action 

 of Voltaic Electricity and Electricity of Tension Effects of a Voltaic 

 Current Ampere's Theory . Page 361 



SECTION XXXIII. 



Magneto-Electricity Volta-Electric Induction Magneto-Electric Induction 

 Identity in the Action of Electricity and Magnetism Description of a 

 Magneto-Electric Apparatus and its Effects Identity of Magnetism and 

 Electricity 365 



SECTION XXXIV. 



Electricity produced by Rotation Direction of the Currents Electricity from 

 the Rotation of a Magnet M. Arago's Experiment explained Rotation of 

 a Plate of Iron between the Poles of a Magnet Relation of Substances to 

 ; Magnets of three Kinds Thermo-Electricity .371 



SECTION XXXV. 



The Action of Terrestrial Magnetism upon Electric Currents Induction of 

 Electric Currents by Terrestrial Magnetism The Earth Magnetic by In- 

 ductionMr. Barlow's Experiment of an Artificial Sphere The Heat of 

 the Sun the Probable Cause of Electric Currents in the Crust of the Earth, 

 and of the Variations in Terrestrial Magnetism Terrestrial Magnetism 

 possibly owing to Rotation Magnetic Properties of the Celestial Bodies- 

 Identity of the five kinds of Electricity Connexion between Light, Heat, 

 and Electricity or Magnetism 376 



SECTION XXXVI. 



Ethereal Medium Comets Do not disturb the Solar System Their Orbits 

 and Disturbances M. Faye's Comet probably the. same with Lexel's 

 Periods of other three known Acceleration in the mean Motions of 

 Encke's and Biela's Comets The Shock of a Comet Disturbing Action 

 of the Earth and Planets on Encke's and Biela's Comets Velocity of 

 Comets The great Comet of 1843 Physical Constitution Shine by bor- 

 rowed Light Estimation of their Number 385 



SECTION XXXVII. 



The Fixed Stars Their Number The Milky Way Double Stars Binary 

 Systems Their Orbits and Periodic Times Colours of the Stars Stars 

 that have vanished Variable Stars Variation in Sun's Light Parallax 

 and Distances of the Fixed Stars Masses of the Stars Comparative Light 

 of the Stars Proper Motions of the Stars Apparent Motions of the Stars 

 Motion and Velocity of the Sun and Solar System The Nebulae Their 



