 Heliotrope (instrument)

A heliotrope is an optical instrument used for surveying and determining the position of points on the Earth's surface by reflecting sunlight. It typically consists of a small mirror mounted on a tripod or stand, which can be angled to reflect sunlight toward a distant observer. When the light is reflected towards a surveyor or a receiving station, it can be seen from a significant distance, allowing for accurate triangulation and positioning.