What is perhaps the first color specification system, developed in 1677 by the eminent English physician Francis Glisson, is described. Two of the scales for which Glisson provided quantitative data Glisson have been reconstructed: the gray scale in virtual form and the red scale in real form. Reflectance calculations or measurements and calculations of CIELAB L*a*b* values indicate that the two scales have a significant degree of uniformity despite the simple method used by Glisson to construct them.