THEDEVElflPMtNTflF 



ELECTRICAL TCCHPlflBY 



INTHElDtllCEmiRY: 



l.The Electrochemical Cell 

 and the Electromagnet 



by W. James King 



This paper — first in a series tracing the early history of electrical 

 invention — deals ivith two devices basic to most of the later inventions 

 in this field. 



Starting with the early researches of Luigi Galvani and Alessandro 

 Volta in the late 1700' s, it highlights developments involving the 

 electrochemical cell and the electromagnet during the period that 

 culminated in the invention of various electric motors in the mid-19th 

 century . 



Among the devices described and illustrated are objects in the 

 collections of the Smithsonian. They iticlude the 1831 electromagnet 

 of Joseph Henry, later to become first head of the histitution, and 

 the U.S. Patent Office model of Thomas Davenport' s electric motor, 

 the first to be patented in America. 



The Author: W. James King— formerly curator of electricity 

 in the United States Natioital Museum, Smithsonian Institution- 

 is associated ivith the American Institute of Thy sic s. 



MUCH of electrical technology depends upon an 

 understanding of the properties of a coil of 

 wire about an iron core. When an electric current 

 is sent through a coil, the coil becomes an electro- 

 magnet that produces a mechanical force which may 

 be turned on and off; moreover, this mechanical 

 force may be controlled at a distance and in any 

 arbitrary manner. On the other hand, an electric 

 current is induced in the coil if a magnet is moved 



near it. Almost all electrical machinery with moving 

 parts depends on these simple properties. 



Static electricity had been known for some time 

 before electromagnetism was discovered. However, 

 it was not until the chemical cell was devised and 

 made practical that electromagnets could be applied to 

 invention. The first part of this article deals with the 

 story of the chemical cell, together with some of its first 

 commercial applications; the second part concerns elec- 

 tromagnets and how they were first applied to motors. 



PAPER 28: DEVELOPMENT OF ELECTRICAL TECHNOLOGY IN THE 19TH CENTURY: I 



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