Definition of "galligaskins"

He was generally seen trooping like a colt at his mother's heels, equipped in a pair of his father's cast-off galligaskins, which he had much ado to hold up with one hand, as a fine lady does her train in bad weather.

1819 June 23, Geoffrey Crayon [pseudonym; Washington Irving], “Rip Van Winkle”, in The Sketch Book of Geoffrey Crayon, Gent., number I, New York, N.Y.: […] C. S. Van Winkle, […], pages 64–65