Green’s Dictionary of Slang

(US Und.) boots.

1848		Ladies’ Repository (N.Y.) Oct. VIII:37 317/1: Squills, boots.
1851		G. Thompson Jack Harold 60: I got a pair of flash kicks, a tog and cady too, / A gallus jerve, a pair of squills so polish’d and so new.
1891		Emporia Dly Repub. (KS) 28 Apr. 3/2: Trousers are ‘kicks,’ shoes are ‘squills’ or ‘stamps,’ and boots are ‘churns’.