Abstract: An apparatus for measuring or observing parameters representative of the coagulation and/or the lysis of a coagulable liquid, such as blood, comprises a torsion thread, a driving body supported by the torsion thread to be dipped in the liquid, a vessel containing the liquid is oscillated with a predetermined angular amplitude and period around an axis substantially identical with the torsion thread.Detection means comprise an inductor driven by the thread and a fixed position-detector which delivers an electrical signal representative of the amplitude of the oscillations of the torsion thread.The torsion thread is constituted by a wire stretched between two anchoring points and bearing the mass.