Neutral buoyancy diver maintains neutral buoyancy by continuous correction, usually by controlled breathing, as neutral buoyancy is an unstable condition for a compressible object in a liquid. The mathematician Archimedes discovered much of how buoyancy works more than 2000 years ago. In his research, Archimedes discovered that an object is buoyed up by a force equal to the weight of the water displaced by the object. In other words, an inflatable boat that displaces 100 pounds (45 kilograms) of water is buoyed up by that same weight of support. An object that floats in the water is known as being "positively" buoyant.
Legend of the Leather Bridge Legend of the Leather Bridge There is a legend of the Leather Bridge () in several regions of Germany and Switzerland. The word "lederne" could also have meant "ladder" or "lantern". According to legend, there was once a leather bridge crossing the Elmstein valley between the Palatine castle of Erfenstein, high above the left bank of the Speyerbach river, and a second castle, Spangenberg, on the opposite side of the valley. Two brothers, or at least two close friends, who visited each other frequently, decided to build the bridge in order to avoid having to take the difficult path through