As the curved plates of the Rotary press made the stamps slightly larger, it is relatively easy to discern which stamp is flat plate and which is a rotary press stamp. First, select any perf Washington Franklin stamp or the first issue Washington Franklin 1 cent or 2 cents. These are the stamps with the numbers one and two spelled out instead of numbers displayed. I chose the latter alternative, as shown in the first image above.

Then cut out squares at each corner, as shown in the second image above. Placing the stamp, you wish to test under your cut-out stamp to test if the frame lines match. If, as in the last image shown above, the frame lines are outside the top stamp in either the top, bottom, or sides then you have a rotary stamp. If the lines are in the same place, you have a flat plate stamp, as shown in the third image.

This test works with any value stamp.

Using this photograph, the stamp designer Clair Aubrey Huston added the toga cord and button. The engravers of the stamp were M.W. Baldwin (who engaged almost all US stamps of this era. The lettering was engraved by Robert F. Ponicka and Edward M. Hall.

A #408 pair which has perforations added and for good measure a fake joint line drawn in.