The measuring device (10) can be fitted into a tubular conduit. In operation, the fluid to be measured flows through the device (10). The device has a single, straight measurement tube (13) with a longitudinal axis (131), an inlet end and an outlet end (11,12). A carrier is fixed to the inlet and outlet ends. From the carrier, a long heavy line runs from the carrier parallel to the longitudinal axis (131) of the tube and does not meet it. The device also has a jib or boom mass (15) fixed in the middle between the inlet and outlet ends. In operation the mass (15) causes the tube to oscillate either in a first oscillation base mode or a second, higher frequency base mode. An exciting arrangement (16) sets the tube to always oscillate in the second mode. The exciting arrangement (16) is arranged somewhere in the middle of the inlet and outlet ends.; A sensor (17,18) is provided for each of the inlet and outlet end oscillations of the tube. Each sensor is arranged at the same distance from the inlet or outlet end respectively.