(Another good one for a boy. The colors of the blouse and cap could be altered; jockey silks come in a wide range of colors and patterns, each representing a different owner.)
Blouse of blue satin with white rings, cap of same material with white peak. White cloth breeches; black boots with white tops.
Source: Masquerades, Tableaux and Drills. New York: The Butterick Publishing Company, 1906.