Light Telegraphs

Status: 🌿

Using just a single difference to communicate the alphabet became prevalent in the 17th century.

In combination with the telescope (invented 1608), the X device enabled utilizing this method across much greater distances. This meant a message could be sent from London to Paris, which instigated a surge in new inventions for passing differences.

The shutter telegraph was developed by Lord George Murray. Technology from 1795 demonstrates the use of a single difference to communicate anything.

Composed of six rotating shutters, in a two-by-three grid.

[Image source](https://www.researchgate.net/publication/241060234_A_Brief_History_of_Early_Museums_Online)

Each shutter could be either open or closed.

That is 2 to the power of 6, which means 64 differences in total.

Example:

a decision tree visualization of this creates a path like this:

all the letters of the alphabet and a set of numbers are at the end of the decision tree.

So to get to B, the sequence would be

closed closed closed closed open

Exercise

A Glossary for Information TheoryAbout how it was builtAbout the formattingAbout the processAbout the structureAbout this digital gardenAncient Egypt Writing SystemsAncient Phoenicians Writing SystemAncient Semitic Writing SystemsChannel CapacityDemotic Writing SystemDevelopment of Writing SystemsDevices For Sending InformationElectromagnetic TelegraphsElectrostatic TelegraphsError Correction CodesHamming CodeHieratic Writing SystemHieroglyphics Writing SystemIdeogramsInformation TheoryLight TelegraphsMarkov Chain ModelMathematical Theory of CommunicationModels and TheoriesMorse CodePapyrusPictogramsPolybius squareQuadruplex TelegraphSignal FiresSignaling RateSource CodingTelegraphsThe Gauss-Webber TelegraphThe Rebus PrincipleThe Rosetta StoneVisual TelegraphsWriting Systems: From Symbols to LettersWritten Language