Hemisferium Hanging Altitude Ring dial (40º or 50º Lat.)15th century mariners found a way to estimate their latitude to find their location while at sea. It was based on a well known fact that the height of celestial bodies depends on the latitude. The Altitude sundial takes this name because the parameter of its construction is based on Suns altitude. This brass scientific instrument is available for two different latitudes: 40 or 50. The dial is composed of a circular band punched with two offsetting