  Spectro-polarimetric measurements of the D3-HeI 5876 A line profile in 35
prominences have been performed in 2003 with the Gregory-Coud\'e Telescope in
Locarno. Two different experimental techniques (ZIMPOL and Beam-exchange
method) have been successfully employed to determine all four Stokes
components. Both give compatible results. The preliminary results as well as
the measurement techniques are reported.
