the pressure: G. Ulmer. Invent-L. March 14 2003. http://web.nwe.ufl.edu/~gulmer/disseminar/invent.html.

One kind:

Etlicher het einen fuz
der was michel unde groz
der lief also balde
sam ein tier dat zee walde.
From a 12th Century German poem.

whistles: "We had been hearing noises in the evening for about a week. We heard a shrill, peculiar whistling each evening. We would hear it coming from one ridge, and then hear an answering whistling from another ridge. We also heard a sound which I could best describe as a booming, thumping sound — just like something was hitting its self on its chest. Hank asked me to accompany him to the spring, about a hundred yards from our cabin, to get some water, and suggested we take our rifles — to be on the safe side. We walked to the spring, and then, Hank yelled and raised his rifle, and at that instant, I saw it. It was a hairy creature, and he was about a hundred yards away, on the other side of a little canyon, standing by a pine tree. It dodged behind the tree, and poked its head out from the side of the tree. And at the same time, Hank shot. I could see the bark fly out from the tree from each of his three shots. Someone may say that that was quite a distance to see the bark fly, but I saw it. The creature I judged to have been about seven feet tall with blackish-brown hair. It disappeared from our view for a short time, but then we saw it, running fast and upright, about two hundred yards down the little canyon. I shot three times before it disappeared from view." F. Beck, "I Fought the Apeman on Mt. Saint Helens." http://www.rfthomas.clara.net/classics/beck.html

to perceive: M. Elide, Myths, Rites, Symbols: A Mica El aide Reader. New York, 1976. Viol. 2. p.338.