The
Invention
optical telegraphy was invented in the 1790s. According to this system a large
number of signals, in some cases as many as 100,000 different ones, could be
sent from high signal posts or similar structures. The posts would normally
be placed at intervals of about 10-15 kilometres. When a station sent off a
signal, it was repeated along the entire row of posts, often for several hundred
kilometres. It was said that a signal could travel from Copenhagen to Schleswig
in about 18 minutes.
The
telegraph dictionary, 1801. Post & Tele Museum.
The many signals were translated via a code book from numerical values to letters,
words or sentences. The dictionary contained more than 30,000 different words
and sentences, ranging from everyday words (3,467 = pin prick) to sentences
for use in times of war (6,943 = the enemy is attacking).
