Optical telegraph in the setting sun
Between 1793 and 1854, a number of telegraph lines were established, radiating from Paris and passing signals via optical means. The stations were 9 to 12 km apart. The one in the photo is a reconstruction. The original on the same spot was intended to form part of the line from Paris to the fortress in Landau via Metz. Construction of the line began in 1793 but was never completed.
