Original Image Tube Spectrograph built in the early 1960s by W. Kent Ford, Jr., which he then used in collaboration with Vera Rubin to explore an observational problem she had developed: to determine the detailed rotational properties of galaxies. The cascaded image tube developed by Ford at the Carnegie and then manufactured by RCA improved quantum efficiency of photographic detectors by over a factor of ten and made it feasible to perform difficult observational programs like this. Analysis of observational data from this instrument led Rubin to the conclusion that there was a huge amount of unseen mass distributed throughout the visible matter in galaxies causing them to rotate like rigid bodies. This observation yielded evidence for the existence of dark matter that stimulated general acknowledgement that it forms much of the mass in the universe. For her revolutionary work, Vera Rubin was the second woman in history to be awarded the Gold Medal of England's Royal Astronomical Society.