"Worldly Goods : The Arts of Early Pennsylvania," at the Philadelphia Museum of Art, 1999.
Lindsey, Jack L., Worldly Goods: The Arts of Early Pennsylvania, 1680-1758 (Philadelphia: Philadelphia Museum of Art, 1999)
The German mystic pietist Johannes Kelpius (1673-1798) is said to have brought this sundial to Germantown, Pennsylvania. It is believed to have been owned later by Christopher Witt and Benjamin Franklin. Franklin presented it to the American Philosophical Society.