(Above: My photo of "Indian Cave" see: http://wakinguponturtleisland.blogspot.com/2011/12/indian-cave.html )
"Sweat Houses in the Southern New England Area" by Eva Butler.
A word new to me "Pesapungganute" appears in the article.
Stone pile mention: "Several Mohegan-Pequot deeds mention sweat-houses. Daniel Comstock in 1730 deeded to his son John, land on the Thames River in what is now the town of Montville. It was a piece of meadow, to witt, fresh meadow at a heap of stones at a place called the Hot House." (Land Records, Vol. IX, p. 149, City Hall, New London, Connecticut.)
Roger Williams defines a Pe’suponck / sweatlodge as “a kind of cave or cell, built on the side of a hill. It is six or eight feet across, and usually situated near a stream. It is prepared for use by building a fire on top of a pile of stones. When the stones are heated through, they put the fire out, while the stones continue to hold their heat. At this point between ten and twenty men enter the lodge, having left all their clothes at the door, with one person to guard them. They then sit around these hot stones for an hour or more, taking tobacco, talking and sweating together. Their sweating has two benefits; it cleanses the skin and it cures some diseases. When they come out of the sweathouse, summer or winter, they plunge into the stream to cool off. Though it seems amazing, they do not seem to suffer from the sharp change in temperature.”
Hadassah Davis (What Cheer, Neetop?" 1986) adds below the translation: “Sweat lodges were used by several groups of Indians, among them the Nipmucks of Massachusettts. They built ceremonial stone sweat lodges, called pesu-poncks, that were used for purification rituals: and many of these chambers can be found near Nipmuck villages (Nipmuck Indian Council of Chaubunagunamaug).”