Act IV - Following a year of R&D, the first prototype is created. The time is accurately indicated thanks to a rectangular capillary measuring 1.7/03mm, machined in a circle between two layers of Plexiglas making up the watch glass. Created using rolling membranes, the flexible reservoirs are trapped intransparent cylinders. The force required to move the liquid is transmitted by a cam, which replaces the hour hand. The concept is demonstrated and the patents registered by Preciflex.