CH. XXXV. OERSTED. 341 



CHAPTER XXXV. 



SCIENCE OF THE NINETEENTH CENTURY (CONTINUED). 



Oersted discovers the effect of Electricity upon a Magnet — Electro- 

 magnetism — Experiments by Ampere on Magnetic and Electric 

 Currents — Ampere's Early Life — Direction of the North Pole of the 

 Magnet depends on the course of the Electric Currents — Magnetic 

 Currents set up between two Electric Wires — Electro-magnets 

 made by means of an Electric Current — Arago magnetises a Steel 

 Bar with an ordinary Electrical Machine — Faraday discovers the 

 Rotatory Movement of Magnets and Electrified Wires — Produces 

 an Electric Current by meaas of a Magnet — Seebeck discovers 

 Thermo-electricity, or the production of Electricity by Heat — 

 Schwabe discovers Periodicity of the Spots on the Sun — Sabine sug- 

 gests a connection between Sun-spots and Magnetic Currents — This 

 proved in 1859 by observations of Carrington and Hodgson — 

 Electric Telegraph — Wheatstone — Cooke — Steinheil — Morse — 

 Bain. 



Oersted discovers the Effect of Ehctricity upon a Mag- 

 net, 1820. — We left the history of electricity at p. 264, at 

 the point where Volta had shown in 1 800 that two diffe- 

 rent metals joined by a wire and placed in acid and water 

 will set up two currents of electricity flowing in opposite 

 directions from one metal to the other along the wire, and 

 back through the water. Every galvanic battery, that is, an 

 apparatus for producing electricity by chemical action, is 

 made on this principle. You will hear of Grove's battery, 

 Bunsen's battery, Daniell's battery, and many others, all of 

 which have been invented in the present century ; but all 



