What is "bowstring bridge"

Bowstring \Bow"string`\, n.

1. The string of a bow.

2. A string used by the Turks for strangling offenders.

   Bowstring bridge, a bridge formed of an arch of timber or iron, often braced, the thrust of which is resisted by a tie forming a chord of the arch.

   Bowstring girder, an arched beam strengthened by a tie connecting its two ends.

   Bowstring hemp (Bot.), the tenacious fiber of the Sanseviera Zeylanica, growing in India and Africa, from which bowstrings are made.
   --Balfour.