Swearing by Swans

Though I can give no reason why the birds of Juno should have been invoked as witnesses to an oath, the Query about them has suggested to me what may perhaps appear rather an irrelevant little note. Cooper, in his *Raven's Nest*, makes Mr. Aristobulus Brag use the provincialism "*I swanny*;" "by which," observes the author, "I suppose he meant—*I swear!*" Of course, this has nothing to do with swearing by swans, more than sounding like it; argument of sound being very different from sound argument. Mr. Cooper does not seem to have given a thought to the analysis of the phrase, which is no oath…