Why a Bell Seems to Keep Sounding After the Strike
The lingering ring is in the listener's ear, like the sun's afterimage in the eye
Two paragraphs of mirror-writing set out a note 'on the sound that seems to remain in the bell after the strike.' Leonardo argues that the lingering ring is not in the bell but in the ear of the listener, which retains the likeness of the heard stroke and loses it gradually, exactly as the impression of the sun fades from the eye. A 'contrary proof' adds that if the sound truly stayed in the bell, laying a palm on it would not silence it; yet we see that touching the struck thing stops the sound at once. Faint mechanism outlines show through from the recto below the text.
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The lingering sound is in the ear, not the bell
Leonardo denies that the sound persisting after a bell is struck lies in the bell itself. It is in the ear of the listener, which keeps the likeness of the heard stroke and lets it go little by little.
Compared to the sun's fading afterimage in the eye
The gradual loss of the retained sound is likened to the impression of the sun in the eye, which fades little by little until it is seen no more. The acoustic aftertone is thus explained by analogy with an optical afterimage.
Contrary proof: a hand on the bell silences it
If the sound really remained in the bell, touching it with the palm — especially at the start of its force — would not stop it, since the ear would hold it just the same. But experience shows that laying a hand on the struck thing makes the sound cease at once.