Field studies which were performed in 1990 on a strain network yielded all quantities which are necessary to solve the mass-conservation equation with respect to the melting rate underneath the Filchner-Ronne Ice Shelf, Antarctica. Repeated electro-optical distance measurements, direction observations and absolute positioning using satellite methods (GPS), determined strain rates and ice-flow velocities. Due to the high precision of the used field techniques, about one month between re-observations was sufficient to estimate a melting rate of 1.5 m/a within 0.15 m/a of accuracy. -from Authors