ἵνα δ᾽ εἴη μέτρον ἐναργές τι πρὸς ἄλληλα βραδυτῆτι καὶ τάχει καὶ τὰ περὶ τὰς ὀκτὼ φορὰς πορεύοιτο
This καὶ τὰ περὶ τὰς ὀκτὼ φορὰς πορεύοιτο appears to be ungrammatical and has no meaning, so it was emended into καθ’ ἅ in the commentary. Were the scribes completely spaced out?