Abstract: A device for positioning a first element relative to a second element which comprises: a horizontal panel on the upper face of which the first element is able to be disposed and which has a housing able to hold the second element; and first abutment against which the first element is able to come into abutment in a first adjusting direction and second abutment against which the first element is able to come into abutment in a second adjusting direction perpendicular to the first adjusting direction, the first and second abutment being mounted on the panel projecting from the upper face of the panel, The device comprising an arrangement for adjusting the position of the first abutment in the first adjusting direction and an arrangement for adjusting the position of the second abutment means in the second adjusting direction with respect to the position of the housing in the panel.