They came from the estate of the late Joseph P. Ourdan, one of the old portrait engravers of the National Bank Note Co.  Ourdan worked on the portraits of many of the old United States stamps, engraving the medallions for the 1861, 3¢ Washington, the 1863, 2¢ black Jackson, and the 1866, 15¢ Lincoln, to mention a few, and he was an expert in his field.

Of the seven die proofs, the 6¢ Lincoln and the 7¢ Stanton medallions are each in black, while the 15¢ Webster is in green.  The Hamilton medallion for the 30¢ stamp is in four colors, ultramarine, deep rose, brown and green, and the four proofs were taken in progressive stages of the die engraving.  All are on India paper, countersunk to die size on cardboard, of the large die proof style then customary.  They are masterpieces of miniature portrait engraving, an art which might be lost, except that the big bank note companies teach and bring up their own men.  After long apprenticeship, some make good, and other show no aptitude for the work and have to be released.