The University of Oklahoma Libraries have done a wonderful job with their history of science collections. Visitors to the site will find seven collections here to keep their minds busy. Their number includes "Copernicus's De revolutionibus" and "Scientific Instruments and Historical Artifacts." Of course this first volume is nothing less than a classic, presenting Copernicus's evidence and arguments in support of heliocentric theory. This volume also contains extensive marginalia from a circle of astronomers located in Paris in the decade following the book's publication in 1543. Moving on, the "Scientific Instruments and Historical Artifacts" area contains 16 wonderful items, including an ancient Mesopotamian cuneiform tablet and videos of historically significant refractometers.