The origin of signalling principles, their purpose and development since the 4th century BC are described. Claude Chappe' s research on the peculiarities of human vision and the rationale for the choice of colors for the optical telegraph are presented. These principles are used in modern rail and road signaling systems with slight modifi cations to refl ect the development of technology. The transmission apparatus and the Claude Chappe alphabet are presented, documentary examples of its use in France are proposed, and the main disadvantages of this principle of data transmission are indicated. Further in the article, an alternative principle of data transmission using a single semaphore wing in an optical telegraph is presented. It was developed and introduced in 1798 between Madrid and Cadiz (Spain) by Agustin de Betancourt. The article shows the diagrams of the optical telegraph apparatus of Agustin de Betancourt, and also gives its comparison with fi rst mechanical signals used in railway transport. With references to historical documents and evidence, the evolution of the optical telegraph by Agustin de Betancourt from data transmission systems between cities to systems for the exchange of information between neighboring railway posts and stations on the fi rst railway lines is presented. The evolution of the telegraph from mechanical devices announcing the train approach to the railway post to the signals for train drivers thanks to the change of wing position is shown. As a transitional stage from mechanical to electrical signals in railway transport, the principle of operation of semaphores with kerosene lamps lit at night with light fi lters mechanically connected to the position of the wing is explained. Based on development of mechanical signals, the historical reasons for signal aspect with two lamps in diff erent modern signalling systems are presented. The article opens a new, previously little-known page of the activities by Agustin de Betancourt, who was not only the fi rst rector of the fi rst transport high school in Russia but also one of developers of data transmission systems used optical telegraph. His inventions such as mechanical signal with one wing are using in improved form in railway signalling systems up today.
A refinement-based development of a distributed signalling system
