In 1834, Carl Jacobi discovered his uniformly rotating self-gravitating ellipsoids (the Jacobi ellipsoid). A comprehensive list of ellipsoids is given under Earth ellipsoid. Traditional reference ellipsoids or "geodetic datums" are defined regionally and therefore non-geocentric, e.g., ED50. There are various forms of transverse or oblique stereographic projections of ellipsoids. These geocentric ellipsoids are usually within of the geoid. Common designs include spheres, boxes, ellipsoids and toroids. Various different ellipsoids have been used as approximations. Floats are made in many different shapes, with spheres and ellipsoids being the most common. Other phases, including shapes such as ellipsoids, cylinders, and bilayers, are also possible. Many different reference ellipsoids have been used in the history of geodesy. Quadric surfaces include ellipsoids (including the sphere), paraboloids, hyperboloids, cylinders, cones, and planes. Instead, the geoid of the earth is described by many ellipsoids. These "galaxies" had diverse morphologies, ranging from ellipsoids to disks. These will be ellipsoids with foci at the transmitter and receiver. For more results on void percolation around ellipsoids and elliptical plates, see .