Electromagnetic Telegraphy

Samuel F.B. Morse and Alfred Vail

Samuel F.B. Morse (1791-1872)

Joseph Henry (1797-1878)

The Morse-Vail-Henry Telegraph



Electromagnets -- The Crucial Enabling Technology

" ... It is certain that Joseph Henry was important to the history of the telegraph in two ways. First, he was responsible for major discoveries in electromagnetism, most significantly the means of constructing electromagnets that were powerful enough to transform electrical energy into useful mechanical work at a distance. Much of Morse's telegraph did indeed rest upon Henry's discovery of the principles underlying the operation of such electromagnets.

"Secondly, Henry became an unwilling participant in the protracted litigation over the scope and validity of Morse's patents. ..."

"... Joseph Henry began his research into electromagnetism in 1827, while he was an instructor at the Albany Academy in New York. By 1830, he achieved two major breakthroughs .... His first crucial innovation, which he demonstrated in June 1828, was to combine Schweigger's multiplier with Sturgeon's electromagnet to obtain an extremely powerful magnet. While Sturgeon loosely wrapped a few feet of uninsulated wire around a horseshoe magnet, Henry tightly wound his horseshoe with several layers of insulated wire. In March 1829 he demonstrated an electromagnet with 400 turns, or about 35 feet, of insulated wire. This magnet, Henry remarked later, "possessed magnetic power superior to that of any before known."

"...  Henry did set out to demonstrate the practicability of an electromagnetic telegraph immediately after his paper appeared. His prototype consisted of a small battery and an "intensity" magnet connected through a mile of copper bell-wire strung throughout a lecture hall. In between the poles of this horseshoe electromagnet he placed a permanent magnet. When the electromagnet was energized, the permanent magnet was repelled from one pole and attracted to the other; upon reversing battery polarity, the permanent magnet returned to its original position. ... Henry caused the permanent magnet to tap a small office bell. He consistently demonstrated this arrangement to his classes at Albany during 1831 and 1832." (Source)

Sturgeon's electromagnet
of 1824

Henry's "Yale" magnet
of 1831

Henry's horseshoe magnet
of 1829

Henry's more powerful,
multicoil magnet of 1831

Henry's classroom one mile
"telegraph" of 1831-32

The Role of the Entrepreneur  -- Samuel Finley Breese Morse

"... Morse's ingenuity was in combining a simple electro-mechanical system with some sort of "linear" coding.  Samuel F.B. Morse ingeniously foresaw the newly discovered principle of electromagnetism in combination with some sort of "linear" coding as the key to developing a truly practical telegraphic system.  It could provide the relative simplicity and ruggedness needed for the equipment.  Like Marconi half a century later, his vision to combine these newly discovered principles and the entrepreneurial drive to bring them into use made telegraphy what it became in the field of communication for many decades.  Two features were needed: equipment and a suitable code.   As originally conceived it was to be a self-recording system, inscribing the code signals on a strip of paper tape to be read by eye.  There was no thought given to "reading" it by ear alone."  (Source)

"... Samuel F. B. Morse was born in Charlestown, Mass., on the 27th of April, 1791, but a little over a mile from Franklin's birthplace. He was educated as an artist, and won high triumphs as such, but was marked as a lover of science from his earliest days.  His life was subject to more than the usual vicissitudes of an artist's existence.  After traveling extensively in Europe and studying there, we find him sailing on the packet ship Sully, for the harbor of New York, in 1832.  Philip Hone, in his interesting diary, states that among the passengers on his ship was S. F. B. Morse, the artist and president of the Nationa1 Aeademy of Design.  On board the ship Morse had his interest excited by a conversation in which Dr. Charles T. Jackson was the leader, who spoke of some of the wonders of electricity and of the electrical magnet. This seems to have fixed firmly in Morse's mind the idea that an electric telegraph could be constructed with the electric magnet as a basis. It engrossed his mind throughout thevoyage, and during the six weeks which it lasted he jotted down in his note book different sketches of a proposed system of electrical telegraphy. He practiced his art and experimented with the telegraph, the latter, during the next few years, gradually wooing him from his brush.  Prof. Daniel, of London, in 1835 invented the constant current battery, which proved a powerful adjunct to Morse's work. He was confronted at once with the difficulty that the current became enfeebled on too long a line, and used the relay circuit to overcome this trouble. In 1837 he explained his invention to Professor Leonard D. Gale, of the University of the City of New York, who assisted him by his scientific counsel, and in the same year he interested in it, Alfred Vail, a son of Judge Stephen Vail, proprietor of the Speedwell Iron Works, Morristown, N. J.  An agreement was entered into between them, Vail supplying the money. The American patent was obtained on October 3, 1837, and Vail in secret quarters at the iron factory worked upon the invention."  (Source)

This is the Historic Message

"What hath God wrought!" -- The Bible, Numbers 23:23

which was sent from US Capitol Building in Washington, DC to the
B&O Railroad Depot in Baltimore on May 24, 1844  (Source)

Click on image twice to read original tape

      Morse's pendulum or "canvas-stretcher" telegraph receiver of 1837, 
showing the recording receiver (1), the portrule (2), type (3), and 
and example of characters produced ( 4 and 5 ).

Sketch of a Morse-Vail receiver

Sketch of a Morse-Vail sounder
A circuit diagram of a simple "Simplex" telegraph.

A circuit diagram of a multiple access "Duplex" telegraph.

This page was prepared and is maintained by R. Victor Jones
Comments to: jones@deas.harvard.edu.

Last updated February 27, 2004