A PreciseExperimental Elucidation of the Apparent VerticalThe existence of intrinsic vertical effects of spinning gyroscopes was examined systematically from the viewpoint of precise measurement, using three types of gyroscopes with largely different characteristics.The most precise weighing techniques, such as a reference tare system and various countermeasures, were applied. Slight and symmetrial mass changes observed in the experiment were explained as the parasitic effect of the balance due to the torque of the spinning gyroscopes, utilizing the attenuation constant change under atmospheric conditions. Consequently, the intrinsic vertical effects were found to be virtually zero in this experiment, and even if existent, were estimated to be neither greater than +0.7mg