The telegraph is defined as any system that allows the transmission of encoded information by signal across a distance. While telegraph systems have used a variety of signaling methods and devices, the term is most often applied to the electrical telegraph development in the 19th century.
The earliest forms of telegraphy were probably smoke, fire or drum signals. In the late 18th century optical telegraphs were invented by Claude Chappe in France and George Murray in England – the semaphore.
Rapid development of the telegraph was based on Hans Christian Oersted’s discovery in 1819 that a wire carrying a current was able to deflect a magnetized compass needle. The Cooke and Wheatstone five needle telegraph of 1837 utilized this phenomenon. This apparatus, which is generally regarded as the first functional electric telegraph, was widely used in Great Britain for railroad signaling.
The needle telegraph, even after improvement, required two or more lines to form a complete circuit. It was also relatively slow and the design of the transmitting and receiving instruments was complex. Something simple and efficient was needed.
In 1825, British inventor William Sturgeon, exhibited the electromagnet for the first time. Sturgeon displayed its power by lifting nine pounds with a piece of iron wrapped with wires through which the current of a cell battery was sent.
In 1830, an American inventor, Joseph Henry, demonstrated the potential of Sturgeon's device for long distance communication by sending an electronic current over one mile of wire to activate an electromagnet which caused a bell to strike. Thus the electric telegraph was born.
Samuel F.B. Morse successfully exploited Henry's invention commercially.
Together with his partner Alfred Vail, Morse developed in 1838 the simple operator key, which when depressed completed an electric circuit and sent a signal to a distant receiver which was an electromagnet that moved a marker that embossed a series of dots and dashes (the Morse Code) on a paper roll. About 1856 a sounding key was developed that enabled operators to hear the message clicks and write or type it directly down in plain language.
Telegraph systems quickly spread across Europe and the United States. With the growing telegraph traffic many improvements followed. Like the duplex circuit, in Germany, that made it possible for messages to travel simultaneously in opposite directions on the same line. Thomas Edison devised a quadruplex in 1874 that enabled four messages to travel at once. The most revolutionary invention was that of Jean-Maurice-Emile Baudot, his time division multiplex invented in 1872.
The following links will help you in this effort:
http://www.chss.montclair.edu/~pererat/perbuild.htm
http://www.terrax.org/comm/morsecode/buzzer2.aspx
http://newtone.ku.edu.tr/v1n2/v1n2p44_47.pdf
http://www.charlesedisonfund.org/Experiments/Edison-pdf/edison_ch6.pdf
http://school.discovery.com/curriculumcenter/electricity/activity2.html
http://www.du.edu/~jcalvert/tel/morse/morse.htm
 Lightning Man : The Accursed Life of Samuel F. B. Morse In this brilliantly conceived and written biography, Pulitzer Prize-winning Kenneth Silverman gives us the long and amazing life of the man eulogized by the New York Herald in 1872 as “perhaps the most illustrious American of his age.” |
