Apparatus comprising a member (6) arranged to revolve about a remote centre of motion (O) and a base link (3) coupled to a mounting fixture (1). A first link (4) and a second link (5) are pivotably coupled to the member at respective distances (L1, L2) from the remote centre of motion (O) and are translatable relative to the base link (3) along a f irst direction and at a f ixed ratio of displacement. The ratio of said respective distances equals said fixed ratio of displacement, enabling the member (6) to revolve about the remote centre of motion. The apparatus is characterised in that it comprises means (7) for generating translational motion of a first element (37) and of a second element (57) along parallel but opposite directions. The means for generating translational motion is provided on the first link (4) and is arranged to provide motion parallel to the first direction. The base link is fixed in a position, the first element (37) is fixed to the base link (3) and the second element (57) is fixed to the second link (5), such that generation of said translational motion of the first element (37) and of the second element (57) enables the first link (4) and the second link (5) to translate relative to the base link (3) with said fixed ratio of displacement.Linvention porte sur un appareil qui comporte un élément (6) agencé pour tourner autour dun centre de rotation distant (O) et une liaison de base (3) couplée à une surface de montage (1). Une première liaison (4) et une seconde liaison (5) sont couplées de manière pivotante à lélément (6) à des distances respectives (L1, L2) du centre de rotation distant (O) et peuvent être translatées par rapport à la liaison de base (3) selon une première direction et selon un rapport fixe de déplacement. Le rapport desdites distances respectives est égal audit rapport fixe de déplacement, ce qui permet à lélément (6) de tourner autour du centre de rotation distant. Lappareil est caractérisé en ce quil comporte un moyen (
