While they were wor­king on another hac­kwork (a plaster plaque com­memorating a doctor, Gawlik, for the hospital in the town of Siewierz), KwieKulik made a series of Activities with mer­cury balls, which leaked from a broken ther­mometer. They arran­ged the balls in a similar way as in Activities with Dobromierz (1972-1974), in relation to some mathematical-​logical operations. This Activity begins with a shot of a TVscreen because as the action occur­red the TV was broadcasting a popular didac­tic science programme on set theory.