Optical telegraph towers in the province of Cuenca

Optical telegraph towers

During the archaeological survey work for the installation of a power line, in the municipality of Cuenca, we stumbled upon, at the top of a hill, a quadrangular tower and three floors high. It was made of stone locked with mortar and with traces of plaster, both outside and inside. The tower had walls guarded in the lower third and straight walls in those of the upper heights, as well as three vaulted pockets that open on each of the facades of the ground floor.

On the main façade, the door is raised on the first floor (which would be accessed by an external staircase) and a window opens on the second floor.

Looking for parallels in the bibliography, we discovered that it was what is known as the Optical Telegraph Tower, a term that, in truth, we did not know until then.

When was optical telegraphy born

Born at the end of the 18th century in France, optical telegraphy would not be implemented in Spain until the middle of the 19th century. It was a strategic system with which the Government intended to connect Madrid with other provincial capitals, ports and borders to reinforce State security. To this end, a network of towers was built located at high points in the terrain, which communicated with each other using complex encrypted codes.

The first optical telegraph was designed by Claude Chappe and approved in 1793 by the French National Assembly in a context in which the speed of political and social events in Europe at the end of the 18th century made it necessary to communicate news quickly.

Optical telegraphy is the embryo of electrical telegraphy, one of the great milestones in the progress of communications during the 19th century and a direct forerunner of modern telecommunications systems.

The telegraph device was placed on a tower located preferably in an elevated place. It consisted of a mast with a crossbar in the upper part that rotated on its central axis, called a regulator; two smaller crossbars, called indicators, hung on each of its ends and also rotated by means of pulleys. The different angular positions adopted by the regulator and the indicators were accompanied by a sign.
However, this system had quite a few drawbacks, such as the transmission of signals during the night or on foggy days. For this reason, the network was only operational for a few years, being abandoned and suffering a progressive deterioration.

It was not until 1844 that a large optical telegraphy network was implemented, of a civil nature and at the service of the government; a late implementation compared to other European countries and practically obsolete from a technical point of view, since in those same years, countries such as France were already experimenting with the possibility of using electricity as a vehicle to emit telegraphic signals, and several power lines were already operating in England.

Optical telegraphy in Spain

Built as optical signal repeater stations, in our country these towers were distributed over three lines that crossed a large part of our geography following old communication routes, today regional and national roads.

Thus, there were 196 locations in Spain that made up the Madrid-Barcelona, Madrid-Irún and Madrid-Cádiz lines, in addition to the branches between Tarancón and Cuenca, and Barcelona and La Jonquera.

In short, as Olivé points out, optical telegraphy in our country represented a phase of transition and preparation of the electrical telegraph network.
The spread in the mid-19th century of the electric telegraph as a public service, together with the construction of the railway line, the modernization of the post office and the expansion and improvement of the road and road network, helped to configure a communication system that was decisive in the creation of a national market and in economic growth and the definitive end of optical telegraphy.

Recently, on August 4, 2020, 16 of these towers, located in the province of Cuenca, have been declared Asset of Cultural Interest with the category of Historic Site, and a perimeter is established around them to protect the immediate environment, regardless of their current state of conservation, taking into account the dual need to preserve their material remains and maintain the visual line between towers.

As a general criterion, environments are adapted to the topography of the land, covering complete cadastral plots as far as possible. When this is not possible due to the characteristics of the terrain or the size of the plots, a circumference of 200 meters in radius is traced, taking as its central point the remains of the towers.

This establishes a series of protective measures for the towers and their environment aimed at preserving this important cultural legacy.

BIBLIOGRAPHY

• Agreement of 14/07/2020, of the Governing Council, declaring the Optical Telegraphy Lines of the province of Cuenca as an Asset of Cultural Interest, with the category of Historic Site.
• CRUZ PEREZ, Linarejos (Dir.); CAPDEVILA MONTES, Enrique; SLEPOY BENITES, Paula (2014): Study of the Optical Telegraphy Network in Spain. Madrid: IPCE, 2014.
• OLIVÉ ROIG (1990): History of Optical Telegraphy in Spain. General Secretariat of Communications. Ministry of Transport, Tourism and Communications.
• SÁNCHEZ RIVERA, J.I. (2012): The Telegraphic Tower: an invariant of Spanish military architecture. Cultural Heritage Studies 08.
• Agreement of 14/07/2020, of the Governing Council, declaring the Optical Telegraphy Lines of the province of Cuenca as an Asset of Cultural Interest, with the category of Historic Site. DOCM 04/08/2020.