What is "to spring an arch"

Spring \Spring\ (spr[i^]ng), v. t.

1. To cause to spring up; to start or rouse, as game; to cause to rise from the earth, or from a covert; as, to spring a pheasant.

2. To produce or disclose suddenly or unexpectedly; as, to spring a surprise on someone; to spring a joke.

   She starts, and leaves her bed, and springs a light.
   --Dryden.

   The friends to the cause sprang a new project.
   --Swift.

3. To cause to explode; as, to spring a mine.

4. To crack or split; to bend or strain so as to weaken; as, to spring a mast or a yard.

5. To cause to close suddenly, as the parts of a trap operated by a spring; as, to spring a trap.

6. To bend by force, as something stiff or strong; to force or put by bending, as a beam into its sockets, and allowing it to straighten when in place; -- often with in, out, etc.; as, to spring in a slat or a bar.

7. To pass over by leaping; as, to spring a fence.

8. To release (a person) from confinement, especially from a prison. [colloquial]

   To spring a butt (Naut.), to loosen the end of a plank in a ship's bottom.

   To spring a leak (Naut.), to begin to leak.

   To spring an arch (Arch.), to build an arch; -- a common term among masons; as, to spring an arch over a lintel.

   To spring a rattle, to cause a rattle to sound. See Watchman's rattle, under Watchman.

   To spring the luff (Naut.), to ease the helm, and sail nearer to the wind than before; -- said of a vessel.
   --Mar. Dict.

   To spring a mast or To spring a spar (Naut.), to strain it so that it is unserviceable.