Origin of barrel vault
Examples from the Web for barrel vault
The height of the interior, from the floor to the centre of the barrel-vault of the nave, is a little over seventy feet.
Barrel-vault: A vault whose cross-section is everywhere the same as if part of a tube.How to judge architecture|Russell Sturgis
Sometimes the ceilings were horizontal, sometimes canted on two sides, and sometimes they take the form of a barrel-vault.
The roof seems to have been a barrel-vault, but great part of it has now fallen in.