City University of New York
History of Chemistry
A great site that has a detailed biography of John Dalton, and illustrations of his original chemical symbols.
University of Houston
University of Houston: Engines of Our Ingenuity: John Dalton's Notation
This is part of a small radio show at the University of Houston. It talks about how John Dalton came up with his version of chemical notation, and how it differs from our version of it today. It is available in audio form also.