X CONTENTS. 



SECTION XXXI. 



Discovery of Electro-MagnetismDeflection of the Magnetic Needle by a 

 Current of Electricity Direction of the Force Rotatory Motion by Elec- 

 tricity Rotation of a Wire and a Magnet Rotation of a Magnet about 

 its Axis Of Mercury and Water Electro-Magnetic Cylinder or Helix 

 Suspension of a Needle in a Helix Electro-Magnetic Induction Tem- 

 porary Magnets The Galvanometer . . . . . Page 314 



SECTION XXXII. 



Electro-DynamicsReciprocal Action of Electric Currents Identity of 

 Electro-Dynamic Cylinders and Magnets Differences between the Ac- 

 tion of Voltaic Electricity and Electricity of Tension Effects of a Voltaic 

 Current Ampere's Theory . 319 



SECTION XXXIII. 



Magneto-Electricity Volta-Electric Induction Magneto-Electric Induc- 

 tion Identity in the Action of Electricity and Magnetism Description 

 of a Magneto-Electric Apparatus and its Effects Identity of Magnetism 

 and Electricity . 322 



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 . 325 



SECTION XXXV. 



The Action of Terrestrial Magnetism upon Electric Currents Induction 

 of Electric Currents by Terrestrial Magnetism The Earth Magnetic by 

 Induction Mr. 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 Electricity of 

 Metallic Veins Terrestrial Magnetism possibly owing to Rotation 

 Magnetic Properties of the Celestial Bodies Identity of the Five Kinds 

 of Electricity Connection between Light, Heat, and Electricity or Mag- 

 netism 329 



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 Halley's 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 Con- 

 stitutionShine by borrowed Light Estimation of their Number . 337 



SECTION XXXVII. 



The Fixed Stars Their Numbers Estimation of their Distances and 

 Magnitudes from their Light Stars that have vanished New Stars 

 Double Stars Binary and Multiple Systems Their Orbits and Periods 

 Orbitual and Parallactic Motions Colors Proper Motions General 



