Green’s Dictionary of Slang

1. (Aus.) a tin container, holding a quart (2 litres) of liquid, used for brewing tea and, when empty, containing a smaller vessel for drinking the tea.

1861		Bell’s Life in Sydney 2 Feb. 3/2: Mrs Bell produced a ponderous Jack Shea, full of the stimulating tipple.
1869		Sth Aus. Register (Adelaide) 18 Aug. 25/6: I filled my ‘Jack Shea‘ and put it on the fire to boil.
1879		‘Australian’ Adventures in Queensland 17: He [...] never, by any chance, irritated her, unless he had previously swallowed at least five inches of strong rum out of a ‘Jack Shea’. Not that that small quantity (a good quart) of alcohol affected his brain [AND].
1881		A.C. Grant Bush-Life in Queensland I 209: Hobbles and Jack Shays hang from the saddle dees. [Footnote] A tin quart-pot, used for boiling water for tea, and contrived so as to hold within it a tin pint-pot.
1884		Capricornian (Rockhampton, Qld) 8 Nov. 9/4: He took a blanket with him, a jack shea and panninikin with bread.
1890		Argus (Melbourne) June 14 4/1: Some of his clothes, with his saddle, serve for a pillow; his ration bags are beside his head, and his jackshea (quart-pot) stands by the fire.
1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 88: JACKSHAY: a tin quart-pot carried by bushmen for making tea. It has a wire handle on the side and tapers like a straight jug but without a lip.
1901		W.S. Walker In the Blood 96: They lit a fire to boil a jackshay of water.
1902		Mercury (Hobart) 7 Jan. 3/4: The Minister of State has approved of uniform and kits [...] jack knife, kit bag, [...] one ‘Jack Shea’ pot.
1908		G. Seagram Bushman All 262: The jackshays were boiled and under the soothing influence of ‘post and rail’ [...] their ordinary natures resumed control.
1923		J. Bowes Jackaroos 238: Is there a jackshay in our camp, or at the dam camp?
1936		Bulletin (Sydney) 29 Jan. 21/4: How many could tell you whether a ‘Jack Shea’ was a pug, a movie star, a fencer or a quartpot? – the last has it.
1945		Baker Aus. Lang. 83: Jackshea or Jack Shay are other nicknames for a quart pot.
2002		‘Aussie Gloss.’ in Mudcat Café 🌐 Jack Shay (Jack Shea) Quart pot, metal drinking vessel / container Rhymes (to the Irish) with tea (pot).

2. a measure between a pint and a quart.

1898

Aus. Town & Country Jrnl (NSW) 15 Oct. 21/4: A jack-shay, or quart and pint internuzzled.