Green’s Dictionary of Slang

1. in pl., money [? SE dot, a dowry].

1859		Matsell Vocabulum.
1881		Trumble Sl. Dict. (1890).
1895		Crowe Aus. Sl. Dict. 25: Dots, money.
1937–84		Partridge DSUE (1984) 333/2: from ca. 1880.

2. (UK Und.) in pl., piano keys.

1930		(con. 1910–20s) D. Mackenzie Hell’s Kitchen 118: Dots ... piano keys.
1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 4: Dots: Piano keys.