reins : Idioms & Phrases
Index
Reins of a vault
(Arch.) , the parts between the crown andd the spring or abutment, including, and having especial reference to, the loading or filling behind the shell of the vault. The reins are to a vault nearly what the haunches are to an arch, and when a vault gives way by thrusting outward, it is because its reins are not sufficiently filled up.
