Pair of compasses, having a first compass portion and a second compass portion which are connected together via a hinge having a locking device, which hinge comprises a hinge member mounted rotatably relative to the first or second compass portion, the locking device being spaced from the axis of rotation of the hinge member, the locking device having a threaded element generating a clamping force and cooperating with a nut (11, 12) in order to clamp the hinge member (13) in the locked state against the first and second compass portions, the clamping force acting perpendicular to the axis of rotation of the hinge member (13).