'The stops' referred to by Hamlet are merely the 'ventages.' The act of covering a hole with the finger or thumb was called 'stopping'; and further, one example of the Fistula Dulcis given by Mersennus has two different holes for the lowest note, one on the right and the other on the left, so that the instrument might be used either by a right-handed or left-handed person. One of these two duplicate holes was temporarily stopped with wax. [The passing play upon 'fret' in the last line should not be missed.]
In the next passage the meaning of stop as applied to Recorders is punned on by Hippolyta, who carries on the play from Lysander's horsebreaking metaphor.
Mids. V, i, 108. The Prologue speaks with all the punctuation wrong.
Theseus. This fellow doth not stand upon points.
Lysander. He hath rid his prologue like a rough colt; he knows not the stop....
Hippolyta. Indeed, he hath played on this prologue like a child on a recorder, a sound, but not in government.
That is—the Prologue has misplaced all his stops—like a young horse that refuses to stop—also like a child who has not learned to stop the holes on the flute à bec.
It is singular that the Virginal, which was the most popular of all the keyed instruments, is nowhere directly named in Shakespeare. There is, however, a reference to the action of the fingers on its keys in the following.
Winter's Tale I, ii, 125. Of Hermione, Queen of Leontes, King of Sicilia, and Polixenes, King of Bohemia.
Leon. —— still virginalling
Upon his palm?