PURPOSE: To make a sheetlike object precisely horizontal by a simple operation and to maintain it in a horizontal state.

CONSTITUTION: The center of gravity of a rectangular plane table 1 is made to coincide with the center of gravity of an equilateral triangle on its back, the center of gravity is used as a fulcrum, wires 32 in which weights 31 of equal weight are attached to lower ends are suspended vertically from the individual vertexes of the equilateral triangle, and the plane table is made automatically horizontal.