Speed of sound in air: Speaker resonates air column over water.

Speed of sound calculated from resonances in a tube closed at one end. Water is slowly released from the tall glass column. A Speaker at the top produces a frequency controlled by the Signal Generator. Points are marked on the glass where the sound reaches maximum intensity. First resonance occurs near the top when the water level has only fallen a short distance. Other resonances are noted, and the wavelength is established. The frequency of the speaker is known; the wavelength is measured, and the Water with Fluorescein speed of sound is calculated. (Speed of sound = wavelength x frequency.)