Meaning of “gambled” in “whose wasted right hand gambled against his left” (Aurora Leigh)

Question

From Aurora Leigh - what is the meaning of gambled here? It's hard to understand. I first thought his wasted right hand was somehow pinned to his left one using the brass button, but the dictionaries have only the "game-of-chance" meaning for the word gamble.

Two hours afterward,
Within St. Margaret’s Court I stood alone,
Close-veiled. A sick child, from an ague-fit,
Whose wasted right hand gambled ’gainst his left
With an old brass button; in a blot of sun,
Jeered weakly at me as I passed across
The uneven pavement; while a woman, rouged
Upon the angular cheek-bones, kerchief torn,
Thin dangling locks, and flat lascivious mouth,
Cursed at a window, both ways, in and out,
By turns some bed-rid creature and myself,—
‘Lie still there, mother! liker the dead dog
You’ll be to-morrow. What, we pick our way,

Answer 1

The child is playing a game of chance, with one hand competing against the other, for want of a companion to play against.

Here are a couple of examples from other works, to show how the phrase is used:

One summer afternoon at Capua I was sitting on a stone bench behind the stables of my villa, thinking out some problem of Etruscan history and idly shooting dice, left hand against right, on the rough plank table in front of me.

_{Robert Graves (1934). I, Claudius.}

I sat near her on the floor, playing knucklebones, right hand against left.

_{Mary Stewart (1970). The Crystal Cave.}

What kind of game of chance might be played with a brass button? Perhaps the button is spun to see how it lands; or perhaps the game is played with some other equipment (for example, knucklebones can be played with small bones or pebbles) and the brass button is the stake or prize.

Answer 2

Your understanding of the word gamble is a bit incomplete. While the most common usage is with games on chance (i.e. betting money), broader sense is an risk:

Gamble

[as a verb] Take risky action in the hope of a desired result.

[as a noun] A risky action undertaken with the hope of success.

So how I would interpret the line is that since the child's right hand is wasted, that is a "risk" to try to get the button away from his left. The child is playing a game with themselves the "desired result" being the right hand winning the button from the left.