Abstract: The tension in a filament is measured by deflecting the filament between two outer contact elements by a centrally-located deflecting contact element. A computer receives signals related to the displacement of the contact members, the force on the deflecting contact member and a plurality of relative displacement intervals of the contact elements. The computer determines a plurality of incremental force values related to the force on the deflecting contact element at each of the displacement intervals and calculates the tension in the filament based on the selected incremental force values.