Rings and poles, Bronx Park - Glass negative photogrpah. Public domain.

Photograph shows children playing on equipment, probably including girls from the Washington Irving High Schools New York City, who were attending a Midsummer Day Festival held at Pelham Bay Park in the Bronx on June 23, 1911. (Source: Flickr Commons project, 2008 and New York Times, June 24, 1911)