Contra-barometer, which means that it works opposite to a normal mercury barometer. The oil rises when the bad weather increases and lowers when it's good weather. This will achieve a scale magnification of 10. This is the improved mercury barometer after an invention by Christiaan Huygens. This barometer is made in Thuringia, Germany, but for the Netherlands, because the weather indications are in Dutch. These kinds of barometers were made from the last quarter of the 19th century until the Second World War. Therefore, its age cannot exactly be determined. The plank is of walnut wood. Scale plate and top plate are of opaline glass, also known as milk glass. They are dyed by hand with glass paint and then burnt in the oven. The barometer works excellent, tap runs smoothly. Height approx. 110 cm, width circa 12 cm. With a protective casing and a glass tap for transport. This instrument cannot be sent. So, it can only be picked up in the Rotterdam region.