A metallic plate adorned with a toothed wheel, some small levers and a transparent capsule containing mercury, hung on thin copper wires, at the centre of a painting on Bologna gesso- based board and linseed oil. On the white background, yellowed by linseed oil, one can recognise a print proof impression from one of the Maison d’artiste portfolio (inv. 2748). An iron frame open to the sides frames the composition, as in the artist’s ‘Interno/Esterno’ exhibition-installation works (inv. 3760).