http://phil.cdc.gov/phil/download.asp Via CDC: “This historic diagram, which had been digitally enhanced and colorized, depicted a cut-away view of the interior of a sanitary privy, thereby, revealing the correct design for the seat and the pit. Published in 1916, this was one of a series of instructional drawings used by the Minnesota Board of Health to train its state public health workers. The purpose of this and other like images, and the training was focused on protecting potable water supplies from bacterial contamination. The descriptive information accompanying this drawing referred to a governmental publication with instructions describing the correct placement and construction of a detached home privy. The specific citation was, ‘Minnesota State Board of Health, The Sanitary Privy, May, 1916, p. 12′ This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.” Scan of 2 d images in the public domain believed to be free to use without restriction in the US.