Water against water
Deep mines were flooded by groundwater. Hell used water from mountain reservoirs (tajchy), which under high pressure drove pistons that pumped water out of the mine. The machine needed neither people nor horses.
Banská Štiavnica
The area around Banská Štiavnica had a network of artificial reservoirs, the tajchy, which served the mines. Today they are popular places for swimming. The town and the technical monuments in its surroundings are on the UNESCO list.
His astronomer brother
His brother Maximilián Hell was a world-famous astronomer and director of the Vienna observatory. In 1769 he observed the transit of Venus across the Sun from Vardø in Norway and helped refine the distance between the Earth and the Sun.