The aim of the present paper is to publish 24 synoptic maps of solar filaments, in which 296 prominence average unambiguous magnetic field vectors were determined by Pic-du-Midi observations between 1974 and 1982, which is the ascending phase of cycle XXI. The magnetic field was determined by interpretation of the Hanle effect observed in the HeI D3 line. Previou the prominence field polarity and prominence chirality were applied to solve the fundamental ambiguity. The meas averaged in each prominence for accuracy reasons. The result is twofold. First, alternating field directions can be observed from one neutral line to the next general field alignment is found along a solar North-South field distorted under the differential rotation effect. The about prominence and their magnetic field coordinates are provided as on-line material associated to this paper.