In the wake of the meteorological network founded by the Accademia del Cimento, three instruments were perfected to detect the characteristics of atmospheric air. Pressure was measured with barometers of the type invented by Evangelista Torricelli (1608-1647); temperature with thermometers developed from those of the Cimento; and humidity with hygrometers that, in the simplest version developed by Vincenzo Viviani (1622-1703), exploited the hygroscopic properties of a paper ribbon.