(noun) - (1) Casting mad people into the sea, or immersing them in water until they are well-nigh drowned, have been recommended by high medical authorities as a means of cure.
--James Pettigrew's Superstitions Connected with Medicine and Surgery, 1844
(2) The Cornish call this immersion boossenning, from beuzi or bidhyzi . . . signifying "to dip or drown" . . . A very singular manner of curing madness in the parish of Altarnun was to place the disordered in mind on the brink of a square pool. The patient, having no intimation of what was intended, was by a sudden blow on the breast tumbled into the pool, where he was tossed up and down by some persons of superior strength till, being quite debilitated, his fury forsook him. He was then carried to church and certain masses sung over him.
--William Borlase's Antiquities of the County of Cornwall, 1758