328 BELL SYSTEM TECHNICAL JOURNAL 



Mills and factories were just beginning to be operated by steam 

 power, having previously been dependent upon water power or man 

 power with occasional use of horses or windmills. Lighting was done 

 principally by sperm oil lamps or by candles. Baltimore was the 

 first American city to adopt gas lighting on a large scale in 1817. Gas 

 was introduced in New York City in 1823, but even after 1830 many 

 large cities went for years without a gas system. In 1833 a petition 

 was addressed to the Common Council of Philadelphia protesting 

 against the use of gas "as ignitible as gunpowder and as nearly fatal in 

 its effects as regards the immense destruction of property." ^ There 

 was no commercial application of electricity. At that time electricity 

 was a matter of Leyden jars and of pith balls, of galvanic batteries and 

 of twitching frogs' legs, of crude galvanometers, and of feeble magnets. 



Such was the condition of this country when Joseph Henry was 

 Professor of Mathematics and Natural Philosophy at the Albany 

 Academy about 1830. 



But "The old order changeth, yielding place to the new," and 

 Joseph Henry was one of those who made major contributions to this 

 change. Just what did Henry do that contributed to the development 

 of the electric art of today? As you have heard from Professor Magie, 

 we may properly claim priority for Henry for the following among his 

 many electrical contributions: 



Henry constructed powerful electromagnets by the use of insulated 



wire on the magnet core and by using more than one layer of 



winding. (1829 and 1830) 

 Henry indicated the proper proportioning of magnet windings, external 



circuit resistance and electrical battery arrangement for effective 



operation. (1830) 

 Henry constructed the first motor embodying an electromagnet and a 



commutator. (1831) 

 Henry constructed the first telegraph using an electromagnet as the 



receiving element and demonstrated its operation with a line wire 



over one mile long. (1831 and 1832) 

 Henry discovered the property of self-induction of electrical circuits. 



(1832) 

 Henry constructed and operated the first electromagnetic relay. 



(1835) 

 Henry determined that by the proportioning of the windings of two 



coils in inductive relationship the voltage in the secondary circuit 



could be stepped up or stepped down. (1838) 



i"A Popular History of American Invention," W. Kaempffert, 1924, Vol. 1, 

 p. 554. 



