The hulks or lighters, on board of which felons are condemned to hard labour. Mr. Campbell was the first director of them. See Academy and Floating Academy.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Camp Candlestick * Canary BirdNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes