_a b_ the tendon and ankle in raising the heel approach each other
by a finger's breadth; in lowering it they separate by a finger's
breadth.

[Footnote: See Pl. XXII, No. 2. Compare this facsimile and text with
Pl. III, No. 2, and p. 152 of MANZI'S edition. Also with No. 274 of
LUDWIG'S edition of the Vatican Copy.]