A Plaine and Easie Introduction to Practicall Musicke

The Tenor part expreffeth the leffer moode perfect, that is, three Breeues to the Longe, the blacke Longs containe but two Breeues.
This is imperfection, whereof hereafter.

But when a white Breefe or a Breefe rest doeth immediatly follow a Longe, then the Longe is but two Breeues, as in your Tenor appeareth. Your Base expreffeth time perfect, where euerie Breefe containeth three Semibreeues, except the blacke, which containeth but two.

Discantus.

Augmentation.
Three staves of music notation for the Discantus part in white mensural notation. The clef is a C-clef (soprano) and the time signature is a circle with a central dot, indicating prolatio perfecta.

Altus.

Three staves of music notation for the Altus part in white mensural notation. The clef is an alto C-clef and the time signature is a circle with a central dot.

Tenor.

One staff of music notation for the Tenor part. It features black mensural notation with ligatures and long notes. The time signature is 'O2'.

Bassus.

Time perfect.
Two staves of music notation for the Bassus part in white mensural notation. The clef is an F-clef (bass) and the time signature is a circle with a central dot.