2672: Heliograph Apr 11, 2022

Morse code was used along with early technologies that transmitted data across great distances. A variety of media were used, but things like optical telegraphs or electric telegraphs required a certain amount of infrastructure and constant operators. Conversely, the heliograph was used, most often with Morse code, as a way to send a signal using the reflection of sunlight in a mirror often on a tripod, which could be shuttered at the correct intervals to create a visual signal. While this necessitated some amount of sunshine and a clear line of sight, they were useful for military use, surveying and forestry, and other remote, outdoor work. In Pakistan, these were standard issue in the military as late as 1975.