Early Encoding Schemes

The first reliable report of a multimessage encoding system is the description by the historian Polybius (ca. 200-118 BCE) of Aeneas's "synchronous telegraph" (ca 350 BCE) (source)

Synchronous Telegraph of Aeneas (source)

In turn, Polybius, building on  ideas of Cleoxenus and Democleitus, designed and described an alphabetic code (ca 150 BCE) based on a "code book" or "code-tablet" concept. (source).

Torch Telegragh of Polybus Concept of "code-tablet" encoding

On May 21, 1684 Robert Hooke (1635-1703) proposed an encoding scheme for an optical telegraph system in a lecture to the Royal Society entitled On showing a Way How to Communicate One's Mind. (source)

 

Hooke's Symbols

(From Semaphore to Satellite,Published by the International Telecommunication Union, Geneva 1965)

 

Hooke's Device (source)

(From Semaphore to Satellite, Published by the International Telecommunication Union, Geneva 1965)

 
 

A dubious representation of a Chappe synchronized telegraph system which is based, more or less, on Hooke's encoding scheme. (source).

See also Lesage's and von Sömmering's letter telegraphs as well as and Chappe's and Edelcrantz's code-book optical telegraphs.