A base shaft 4 with a built-in magnet is rotatably projected on a base 1. An oscillating body 7 has a square substrate 8, a sphere 9, a sphere holder 10 which is rotatable around an axis passing through the center of the substrate and perpendicular to the substrate, and a stopper for fixing the sphere holder at a desired rotational position. The sphere holder holds the sphere fixably at the desired rotational position. A stage is attached to the sphere via a support rod 20. The lower part of the sphere projects downward from the sphere holder and the substrate, and the oscillating body is magnetically coupled to the base shaft at the lower end of the sphere. A lifting body 21 is fitted into the base shaft and fixed at a desired height position by a set collar 22. A recess for accommodating the lower part of the sphere is opened in the lifting body. The oscillating body takes a horizontal position when the lifting body comes into contact with the substrate of the oscillating body, but takes an inclined position when the lifting body descends and one side of the substrate is brought into contact with the upper surface of the lifting body. An angle display mechanism 23 is provided for displaying the tilt angle of the oscillating body at the tilt position corresponding to the height of the lifting body.L'invention concerne un arbre de base (4) muni d'un aimant intégré, faisant saillie de manière rotative sur une base (1). Un corps oscillant (7) comporte un substrat carré (8), une sphère (9), un support de sphère (10) qui peut tourner autour d'un axe passant par le centre du substrat et perpendiculaire au substrat, et une butée pour fixer le support de sphère dans une position de rotation souhaitée. Le support de sphère maintient la sphère fixe dans la position de rotation souhaitée. Un étage est fixé à la sphère par l'intermédiaire d'une tige de support (20). La partie inférieure de la sphère fait saillie vers le bas à partir du support de sphère et du substrat, et le c
