The Secret Mark on the 6¢ Lincoln Bank Note
National Bank Note Company
No secret markScott 137 and 148 - There is no extra shading in the lower ribbon, below "SIX". Note that the color is a much richer, brighter shade of carmine than the later Continental printings.
Continental Bank Note Company
Secret MarkScott 159, 186 and 208 - Four lines of shading have been reinforced in the lower ribbon, below "SIX". Note that the color is a much duller shade of carmine than the National printings and the impression is generally weaker (except on the re-engraved 208).
