Previous Serie XVI Next

Serie XVI, Nr 3

Sphere with three maximal circles and eighteen confocal spherical conic sections.


Mathematical description
The model represents a sphere, with 3 maximal circles on it, and 18 confocal (i.e., sharing a common focus) spherical conic sections. A conic section is a nondegenerate curve generated by the intersection of a plane with one or two nappes of a cone. In this case, the sections correspond to the lines of curvature of the ellipsoid. A line of curvature is a curve on a surface whose tangents are always in the direction of principal curvature (i.e., the maximum and minimum of the normal curvature K at a given point of a surface).

Title model and translation
Kugel mit drei grössten Kreisen und achtzehn confocalen sphärischen Kegelschnitten.
Sphere with three maximal circles and eighteen confocal spherical conic sections.

Text on Sticker and translation
missing sticker.

Designer
Prof. Dr. Edvard Rudolf Neovius
Helsingfors in 1888

Company
E.R Neovius

Original price
Mark 35 (for three models)

Dimension
14,5 cm

Material
Plaster

Literature
Schilling, M., Catalog mathematischer Modelle für den höheren mathematischen Unterricht, Leipzig: Verlag von Martin Schilling, 1911