This symbol is part of a set originally created by Emily Read. It was published in The Pavement magazine, a periodical for the homeless community in London. The symbols are an up to date version of a traditional form of communication used by the homeless. Emily has kindly given her permission for the symbols to shared on Openclipart. Original at http://www.thepavement.org.uk/story.php?story=130
This is the "book plate" page from "Dorothy and the Wizard in Oz", published in 1908. The illustration was by John R. Neill. This copy came from the Internet Archive's PDF copy, which can be seen here:
http://www.archive.org/details/dorothywizardino00baum2
an image from the US government EPA "Sunwise" program. I converted it from PDF format. the source link is here - http://www.epa.gov/sunwise/doc/poster.pdf
