The electrical telegraph is a telegraph that uses electric signals.

Needle telegraphs

The early systems were needle telegraphs invented by Charles Wheatstone and William Fothergill Cooke, and patented in May 1837 as an alarm system.

In early 1845, John Trawell was apprehended following the use of a needle telegraph message from Slough to Paddington on January 1 1845. This is thought to be the first use of the telegraph to catch a murderer. The message was:

A murder has just been committed at Salt Hill and the suspected murderer was seen to take a first class ticket to London by the train that left Slough at 7.42pm. He is in the garb of a Kwaker with a brown great coat on which reaches his feet. He is in the last compartment of the second first-class carriage

The reason for the mis-spelling of 'Quaker' was that the British system did not support the letter Q.

Morse telegraphs

Across the Atlantic, Samuel Morse and Alfred Vail were developing an alternative design. It was capable of transmitting over long distances using poor quality wire. The Morse code alphabet commonly used on the device was also named after Morse.

On January 6, 1838 Morse first successfully tested the device and on February 8 he publicly demonstrated it to a scientific committee at the Franklin Institute in Philadelphia, Pennsylvania. The first electric telegram using this device was sent by Morse on May 24, 1844 from Baltimore to Washington, D.C., and said:

What hath God wrought!

(from the Biblical book of Numbers 23:23: Surely there is no enchantment against Jacob, neither is there any divination against Israel: according to this time it shall be said of Jacob and of Israel, What hath God wrought!).

This was the first practical electrical telegraph system, and subsequently electrical telegraph came to refer to a signaling telegram - a system where an operator makes and breaks an electrical contact with a telegraph key which results in an audible signal at the other end produced by a telegraph sounder which is interpreted and transcribed by a human. Morse and Vail's first telegraphs used a pen and paper system to record the marks of the Morse Code, and interpreted the marks visually however, operators soon realized that they could "read" the clicking of the receiver directly by ear. Systems which automatically read the signals and print formed characters are generally called teletype rather than telegraph systems. Some electrical telegraphs used indicators which were read visually rather than by ear. The most notable of these was the early transatlantic telegraph cable.

Global communication

Within 30 years of its invention, the telegraph network crossed the oceans to every continent, making instant global communication possible for the first time. Its development allowed newspapers to cover significant world events in near real-time, revolutionized business, particularly trading businesses, and allowed huge fortunes to be won and lost in an orgy of investment in research and infrastructure building reminiscent of the 1990s dot-com boom. Few inventions have ever had greater impact.

See also

• telegraphy
• telegraph key
• Undersea telegraph cable
• Charles Wheatstone
• Slough - for more details of the Trawell murder

External links

• http://www.du.edu/~jcalvert/tel/morse/morse.htm