slum

Go to the half built-upon slums behind Battlebridge […] you will find groups of boys […] squatting in the mud, among the rubbish, the broken bricks, the dust-heaps, and the fragments of timber […]

The lower the price of slum the better it is for the operator who can either give more of it out or build up the size of his big prizes. It is the big prizes that bring the play, even though the winner has to be satisfied with a piece of slum for his efforts.