Green’s Dictionary of Slang

1. a wooden colander trough used in gold hunting, into which men shovelled earth; also attrib.

1852		L. Clappe in Shirley Letters (1949) 133: It takes several persons to manage, properly, a ‘long-tom’ [...] The spadesmen throw in large quantites of the precious dirt, which is washed down to the ‘riddle’ by a stream of water leading into the ‘long-tom’.
1854		Soulé, Gihon & Nisbet Annals of S.F. 405: Its own mines wanted every hand that could dig a hole or feed a long-tom.
1865		J.F. Mortlock Experiences of a Convict (1965) 156: Then they constructed a ‘long Tom’ sluice.
1887		J.W. Matthews Incwadi Yami 175: First of all came the ‘Long Tom,’ a trough fitted with ripples, into the head of which gravel was thrown.
1903		Amador Ledger (Jackson, CA) 20 Mar. 3/7: A large amount of gold was extracted and washed by ‘Long Toms,’ sluices and rockers.
1916		H. Lawson ‘Madame Bong Fong’ in Roderick (1972) 772: They used long toms for sluicing and lost as much gold as they saved.
1917		‘Henry Handel Richardson’ Aus. Felix (1971) 6: The noise of spades, chopping the gravel into puddling-tubs or the Long Toms.
1968		(con. mid-late 19C) S. Longstreet Wilder Shore 14: Underneath this colander-like portion of the Long Tom is placed another trough [...] The spadesmen throw in large quantities of the precious dirt, which is washed down to the riddle.

2. the penis; cit. 1855 describes a fig. encounter with a prostitute.

1834		Ely’s Hawk & Buzzard (NY) Mar. 22 3/3: Drawing his long tom tickle bender.
1855		Broadway Belle, and Mirror of the Times (N.Y.) 12 Feb. n.p.: Seeing the other craft hoist all her sails, we became excited, and hauling out our long tom, which was already fully loaded, we commenced fight with the rival craft, and after giving her the contents of our long tom, she immediately surrendered.
1904		Lustful Memoirs of a Young and Passionated Girl 26: He then explained that some men drew out their rod just before spending, others used a syringe, others a rubber bag over their long tom, etc.

3. (US prison) a sawn-off shotgun.

1931–4

D. Clemmer Prison Community (1940) 333/2: long tom, n. A sawed-off shotgun.

4. (S.Afr.) a large can of beer.

1979

M. Matshoba ‘Land of a Dying Illusion’ Call Me Not A Man 145: She was focusing my interest as a prospective customer of the ‘Long Tom’, making sure I clearly understood the unusual capacity of the can.