HISTORY OF ELECTRIC LIGHT 

 Bv HENRY SCHROEDER, 



HAPRISON, NEW JERSEY. 

 EARLY RECORDS OF ELECTRICITY AND MAGNETISM 



About twenty-five centuries ago, Thales, a Greek philosopher, 

 recorded the fact that if amber is rubbed it will attract light objects. 

 The Greeks called amber " elektron," from which we get the word 

 " electricity." About two hundred and fifty years later, Aristotle, 

 another Greek philosopher, mentioned that the lodestone would attract 

 iron. Lodestone is an iron ore (Fe304), having magnetic qualities 

 and is now called magnetite. The word " magnet " comes from the 

 fact that the best specimens of lodestones came from Magnesia, a 

 city in Asia Minor. Plutarch, a Greek biographer, wrote about 

 100 A. D., that iron is sometimes attracted and at other times repelled 

 by a lodestone. This indicates that the piece of iron was magnetised 

 by the lodestone. 



In 1180, Alexander Neckham, an English Monk, described the 

 compass, which probably had been invented by sailors of the northern 

 countries of Europe, although its invention has been credited to the 

 Chinese. Early compasses probably consisted of an iron needle, 

 magnetised by a lodestone, mounted on a piece of wood floating in 

 water. The word lodestone or " leading stone " comes from the fact 

 that it would point towards the north if suspended like a compass. 



William Gilbert, physician to Queen Elizabeth of England, wrote a 

 book about the year 1600 giving all the information then known on 

 the subject. He also described his experiments, showing, among 

 other things, the existence of magnetic lines of force and of north and 

 south poles in a magnet. Robert Norman had discovered a few years 

 previously that a compass needle mounted on a horizontal axis would 

 dip downward. Gilbert cut a large lodestone into a sphere, and 

 observed that the needle did not dip at the equator of this sphere, the 

 dip increasing to 90 degrees as the poles were approached. From 

 this he deduced that the earth was a magnet with the magnetic north 

 pole at the geographic north pole. It has since been determined that 

 these two poles do not coincide. Gilbert suggested the use of the 

 dipping needle to determine latitude. He also discovered that other 

 substances, beside amber, would attract light objects if rubbed. 



Smithsonian Miscellaneous Collections, Vol. 76, No. 2 



