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W. & F. Langenheim
The Lord's Prayer - Containing 268 letters in a space the one thousand part of a square inch. and almost invisible by the naked eye. Made by W. F. Langenheim, Philadelphia
Photomicrograph, slide, enlarged
Private collection of Herbert C. McKay
Photographs prepared by Herbert C. McKay and kindly provided by his grandson Maurice M. Greeson (19 June 2012).