DCHP-1 Online
butter tub [< Cdn F pot au beurre in similar sense, a term used by the fur traders and voyageurs] Slang, Hist. 
jail; guard-house, especially at a police post or trading post.
See also: pot au beurre
- 1927 "Did you ever hear . . . of the Butter Vat?" I made no answer . . . for I had indeed heard of the Butter Vat. The "Pot au Beurre," the half-breeds called it. . . . It was the dungeon of the Northwesters, from which prisoners . . . did not often come out alive.
- 1936 . . . he had a sickening vision of himself lying in a Police "butter-tub " . . . .
- 1954 There was . . . a jail--the pot au beurre, or butter tub, the voyageurs called it--where unruly young men cooled off after some of the worst brawls.
- 1927 "Did you ever hear . . . of the Butter Vat?" I made no answer . . . for I had indeed heard of the Butter Vat. The "Pot au Beurre," the half-breeds called it. . . . It was the dungeon of the Northwesters, from which prisoners . . . did not often come out alive.