"Florence Raulin-Cerceau of the Alexandre Koyré Center in Paris has documented the early attempts at communication with extraterrestrial intelligence (CETI), or what is now often called active SETI.
As early as the 19th century, inventors imagined "sky telegraph" equipment to communicate with the supposed inhabitants of the solar system's planets," Raulin-Cerceau recently wrote with her colleague in the French magazine Pour la Science.
The first of these inventors was Carl Friedrich Gauss, the German mathematician. In the 1820s, he spoke of reflecting sunlight towards the planets with his land surveying invention, the heliotrope. He is also credited with the idea of cutting a giant triangle in the Siberian forest and planting wheat inside."