Nothing funny about feldspar

I was following Bill’s link to Public.Resource.Org’s open letter to the Smithsonian. P.R.O. has a valid (IMO) point about the Muybridge and similar photos being in the public domain, and how there’s a disconnect between the Smithsonian’s stated purpose and their actions regarding the images. However, I went to P.R.O.’s flikr photostream of the Muybridge cyanotypes, and I got confused when I clicked on one.

It has a Creative Commons “Some Rights Reserved” notice on it.