unique c. 1906 antique american medical die cut heavy card stock optometrist's practitioner-patient eye color circular and/or wheel chart. the "davis' engravings of eye colors" was manufactured (and likely patented) by charles t. davis, of brooklyn, ny. in later years davis secured patents for poison pills and surgical needles. the chart contains a total of 13 human eyes with roman numerals corresponding to shades of blue and/or brown found on the chart's sleeve or jacket. with the exception of discoloration, the chart remains in great shape, considering age. salvaged from the office of erwin g. clahassey, m.d., who specialized in diseases and surgery of the eye.