Instantaneous minutes counting required fitting a small snail cam on the arbor of the central seconds chronograph wheel. watchesreplicas.coWhen the central seconds chronograph wheel rotates to the right point, the sliding stone (visible at the northwest part of the chronograph wheel in the graphic) on the minutes-counter lever (M) drops off the edge of the snail cam, making the hook (Mh) to pull the minutes-counter (MW) one-step forward. watches.ink The mounting of the snail cam and the heartpiece (Shp) have such close tolerances, that the position of the stone engaging the snail has been made adjustable. This allows for fine adjustment to be made, after the entire mechanism has been assembled.