and can be moved longitudinally in the direction of arrow 26 beam 30 extends parallel to bearing support 16 and can be moved in the direction of arrow 24 therefore the two beams 28 30 are also arranged in a v shape relative to one another the two v shaped structures of bearing supports 16 18 and beams 28 30 having their free ends facing one another or u201c plugged u201d into one another the free ends of beams 28 30 facing each other are connected to a platform 32 which in turn is supported on the upper side of table 12 via bearings 34 36 38 since carriages 20 22 and beams 28 30 can be moved longitudinally platform 32 is moveable on table 12 in directions 24 26 on its upper side platform 32 has a roof shaped hood 40 which is above the bearing supports 16 18 and carriages 20 22 and is supported on the outer free ends of beams 28 30 hood 40 is made of aluminum plates which have numerous holes so as to reduce the weight of hood 40 it serves for stiffening the arrangement comprising the beams 28 30 and platform 32 the three bearings 34 36 38 of platform 32 form the corners of a substantially equal sided triangle above this triangle a quill 42 is arranged on platform 32 quill 42 can be moved longitudinally in the direction of arrow 44 fig3 this direction being perpendicular to the plane of the table 12 and thus representing the z direction at the lower free end of quill 42 a probe holder 46 is arranged for receiving a measuring probe in the embodiment.