"they had tramped out a strange limping dance round the square; round and again round"

The Native American 'the rain dance' is intended to invoke rain and so ensure a good harvest.

Native American Potawatomi Rain Dance, c.1920
Public DomainNative American Potawatomi Rain Dance, c.1920 - Credit: Potawatomi Agency, Bureau of Indian Affairs
A Rain Dance in Harar, Ethiopia
Public DomainA Rain Dance in Harar, Ethiopia - Credit: Anderson smart/Wikimedia Commons

Some tribes – among them the Zuni – perform the rain dance both to induce precipitation and to cleanse evil spirits from the earth. They believe that the rain they summon contains the spirits of past tribal chiefs, who battle evil spirits in the transitional plane between our reality and the spirit world. The dance also calls for a volunteer to take part in unusual and extreme acts of worship, such as the whipping described in this scene. Feathers and materials of a blue shade (usually turquoise) are worn during the ceremony to symbolise wind and rain. 

Click here to find out more about Pueblo dances and ceremonial dress. 

A Rain Dance Performed at the Karneval der Kulturen (Carnival of Cultures), Berlin
Creative Commons AttributionA Rain Dance Performed at the Karneval der Kulturen (Carnival of Cultures), Berlin - Credit: extranoise at Flickr