Page 139 - Inventions - A Visual Encyclopedia (DK - Smithsonian)

THE NEEDLE TELEGRAPH
In 1837, Englishmen William
Cooke and Charles Wheatstone
patented the first practical
telegraph. Activated by electric
currents, its 5 needles could Letters engraved
on the face
point to 20 letters of the
alphabet to spell out
Five magnetic
received messages. needles turn to
By 1839, it was point at letters.
in use on the CROSSING BORDERS
railways.
The first transatlantic telegraph cable was
laid under the sea between Ireland and COMMUNICATION
Newfoundland, Canada in 1858, by the
SS Great Eastern ship, above. This
reduced communication time between
Europe and North America from 10 days
(a ship’s crossing time) to just 17 minutes.

Terminals used to
connect the wires

Cooke and Wheatstone’s
electric telegraph
SENDING MESSAGES BY ELECTRICITY

Morse and Vail created a machine that worked by pushing the operator
Keys pressed in pairs key down to complete the electric circuit of the battery. This sent the
to send letters
electric pulse along a wire to a receiver at the other end. Here, a
small electromagnet powered by the electric pulse attracts a stylus
that marks a paper tape with either short or long marks, representing
dots and dashes.

Reel feeds the
paper tape. Iron armature
WOW! Operator key drives the stylus.

The first words Lever held Stylus
transmitted by Morse’s up by spring
telegraph were, “What hath
God wrought”, sent Paper
between Baltimore and tape
Washington, D.C.

Receiver
Electric battery Electromagnet

137

US_136-137_308121_Telegraph.indd 137 09/03/2018 15:25