H. Schubert introduced a
numerical knot invariant called the bridge number of a knot. In particular, he
classified the two-bridge knots and proved that they were prime knots. Later,
Murasugi showed that if K is an alternating knot then the matrix of K is alternating.
The latter is true of twobridge knots. The purpose of the following is to give a
somewhat unusual geometric presentation of two-bridge knots from which it will be
seen that they are alternating knots.