Perpetual Calendar in Bois Durci
Perpetual Calendar in Bois Durci. Also has a barometer, thermometer and a small clock. Bois Durci is a composition of fine hardwood sawdust and animal's blood. Heated and compressed in moulds, it becomes hard and can be polished. It is in fact one of the earliest plastics ever made. The first patents were applied for by Frenchman Lepage and later followed up by Latry around 1855
MarqueCalendrier perpétuel en bois durci
MarqueCalendrier perpétuel en bois durci