Mining safety cage. 19th-century artwork of the safety cage developed by Pierre-Joseph Fontaine (1810-1877) in 1849. The cage contains coal being lifted to the surface from a coal mine. The supporting ropes (top) have snapped, releasing a spring (top of cage) that has thrust levers towards the wooden beams on either side. The weight of the cage has driven the ends of the levers into the wood, leaving the safety cage suspended and awaiting retrieval. Engraving published in Mines and Miners (L. Simonin, 1868).