On October 16, 1990, a remarkable active prominence was observed, in H&agr; line, during 113 minutes. The time gap between successive profile recordings was 20 seconds and 339 profiles have been recorded together. We focused our attention on Doppler shift measurements as well as on significant changes in the prominence intensity. We also give a possible explanation of a sudden increment in the intensity of H&agr; line in dependence on the fact if the whole profile originates in one particular place in the prominence or if it is a superposition of the radiation incident from two different, physically unrelated parts of the prominence.