342 NINETEENTH CENTURY. FT. in. 



these are only different and more perfect methods of carry- 

 ing out Volta's discovery. The next great step in the study 

 of electricity was made by Oersted, Professor of Physics at 

 Copenhagen, in 1820, twenty years after the invention of 

 the voltaic pile. 



Hans Christian Oersted was born in 1777, and died in 

 1851 ; he was a very eminent man, and wrote many works in 

 Latin upon chemistry and magnetism, but the one discovery 

 which has made him famous was that of electro-magnetism. 

 We have seen (p. 53) that the invention of the mariner's 

 compass in the fifteenth century arose from Flavio Gioja 

 noting that a needle which has been rubbed along a piece of 

 loadstone always points north and south. But why should 

 the needle lie in this direction ? What force makes it turn 

 round when you leave it free after placing it another way ? 

 Ever since the fifteenth century people had asked this ques- 

 tion, and when Volta and Franklin showed that electrical 

 currents are constantly passing to and fro in our atmosphere, 

 scientific men began to consider whether it might not be 

 some force like electricity which acted upon the magnet ; es- 

 pecially as it had been observed that when a ship was struck 

 by lightning, the needle of the mariner's compass was some- 

 times thrown quite out of its right position. 



Still nothing was really known until the year 1819. In 

 that year, when Professor Oersted was one day making some 

 galvanic experiments at a lecture, it happened that a magnetic 

 needle poised upon a point (as in Fig. 54) was standing 

 near the wire along which an electric current was passing. 

 All at once, when the current was very strong, the needle 

 became excited and began to turn round upon the point. 

 Oersted and his assistants were much surprised at this, and 

 the consequence was that for several months Oersted made 



