Early systems included flag signaling, telegraph and heliographs. Most heliographs of the 19th and 20th century were completely manual. The Mance, Grugan and Pursell heliographs used two tripods, and the others one. In 1893, the number of heliographs manufactured for the US Signal Service was 133. Most heliographs were variants of the British Army Mance Mark V version (Fig.1).