Green’s Dictionary of Slang

to beat hemp in prison; thus milldolling.

1714		A. Smith Lives of Most Noted Highway-men, etc. I 141: Hard Labour in Bridewell, which beating of hemp the Thieves call Mill-Dolly.
1733		Cibber Harlot’s Progress 11: Soon shall I see or hear, / Madam, in Bridewell, milling Doll.
1764		Bloody Register I 125: The facts being plainly proved upon him, he was sent to Mill Doll (to beat hemp in Bridewell).
1780		R. Tomlinson Sl. Pastoral 7: But now she mills doll, tho’ the greens are still there.
1784		H. Lemoine ‘The Clever Fellow’ in Wit’s Mag. 155/1: A saucy, tip-slang, moon-eyed, hen, / Who oft’ mills doll at Block.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1790		‘Bumper Allnight. Esquire’ Honest Fellow 154: When she came to the hempen block / [...] /She lim’d off her duds and mill’d doll in her smock, / [...] /But finding the hemp was damnable tough, / [...] /She threw off her smock and mill’d doll in her buff.
1801		G. Hangar Life, Adventures and Opinions II 73: They were committed to the house of correction, and sentenced to mill doll.
1809		G. Andrewes Dict. Sl. and Cant.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1833		‘Her Muns with a Grin’ in Swell!!! or, Slap-Up Chaunter 50: A cut from the trine — or milldolling line — / Or a Sam darkly met.
1848		Flash Dict. in Sinks of London Laid Open.
c.1850		Duncombe New and Improved Flash Dict.