Spectrally-dispersed MIDI visibilities of R Scl (black thin lines to be read from the scale on the left axis) observed over 14 nights between January 2005 and December 2006 (see Tables 2 and 3). Uniform disk diameters (blue thick lines to be read from the scale on the right axis) are computed from the visibilities at each spectral channel. Error bars are not included for clarity. The data set numbers are defined in Tables 2 and 3.