From the Historical Society of Pennsylvania Medium Graphics Collection [V64] [call # Bb 96 R424]. 

Ricketts is credited with introducing the circus to American audiences after he exhibited daring feats on horseback during performances in Philadelphia and New York City.  His act was something of a variety show, displaying tricks performed both by him and his horses at a Philadelphia theater Ricketts founded at Sixth and Chestnut Streets.  Ricketts later expanded the circus to include jugglers and other performers, eventually hiring America's first circus clown.  Sadly, both Ricketts's New York and Philadelphia circuses would be lost to fires by 1799.