Discovery, as an agent of civilization. 15 



Scientific discovery has in all ages been a most \ 

 powerful agent of civilization and human progress. 

 The discovery of the black liquid which a solution 

 of nutgalls produces when mixed with green vitriol, 

 led to the invention of writing ink ; and a knowledge 

 of the properties of ink and paper prepared the way 

 for the invention of printing, by means of which 

 truth and learning have spread all over the earth. 



The apparently insignificant property possessed 

 by amber, of attracting feathers immediately after it 

 has been rubbed, was known twenty-four hundred 

 years ago, and afterwards led to the discovery of 

 electricity. In later times, Dr. Franklin, by means 

 of a kite, charged a bottle with lightning, examined 

 it, and proved lightning and electricity to be iden- 

 tical. This knowledge, joined to the further 

 discovery, that electricity would pass freely through 

 metals, led to the modern invention of the lightning 

 conductor, by means of which all our great buildings, 

 ships, lighthouses, arsenals, and powder magazines 

 are protected from lightning. 



"Coming events cast their shadows before them:" 

 the discovery of the instant transmission of electricity 

 along wires by Stephen Gray and Wheeler, about 

 the year 1729, fore-shadowed the invention of the 

 electric telegraph. About the year 1819, Oersted, 

 a Danish philosopher, after fifteen years of study 

 and experiment, to ascertain the relation of electricity 

 to magnetism, discovered that if a freely suspended 

 magnetic needle was supported parallel and near to 



