The signatures are of the cachet maker, C. Stephen Anderson.
There are some FDCs of this type at
ihobbs, which states:
"The Cachets prepared by C. Stephen Anderson are favored by collectors who appreciate the uniform consistency of their design, featuring an illustration with an historical narrative printed below it."
FDCs are not as widely collected as they once were, and the market is flooded with them. The Famous American 1c, 2c, and 3c FDCs may bring a dollar to a few dollars each retail, the 5c and 10c covers might go higher.