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 Four Blood Bars warned about having found the legend ""according to what I found written"" in a supposed ""personal manuscript"". Even though one cannot impute the invention of the legend to Beuter with absolute security, it seems clear that the resource of the supposed ""personal manuscript"" either refers to a previous source or was subterfuged to avoid any subsequent criticism. Historian points out that, in any case, whether he was the inventor of Beuter's legend or if the legend is an adaptation of an earlier version that circulated in , the ""personal manuscript"" would not be much prior to 1551. Aragonese historian ,