"W. D. Porter, in the New York Herald, points out a new way to discover murderers. He says: ‘The following method will, in many cases, detect the perpetrators of a murder: It is well known that all objects are actually painted or impressed upon the retina of the eye. - Should a person die a violent death, the object before the eye at the time remains impressed on the retina. If the covering of the eye is scraped down thin, and a powerful magnifying glass applied, his image will be distinctly seen. This was the first discovery of the daguerreotype. Any scientific physician can do this.’"
I’d like to see Mr. Porter’s credentials.
Galveston Weekly News (Galveston, Tex.), Vol. 13, No. 21, Ed. 1, Tuesday, August 12, 1856, Newspaper, August 12, 1856; digital images, (http://texashistory.unt.edu/ark:/67531/metapth79865/ : accessed August 12, 2013), University of North Texas Libraries, The Portal to Texas History, http://texashistory.unt.edu; crediting Dolph Briscoe Center for American History, Austin, Texas.