I recently obtained a plats trip of 3 of the 1909 Lincoln (Sc 367). It has an interesting offset on the back. The plate number on the front is 4984.



However on the back there is an offset in the selvedge only. The plate number on the offset is 4983. Why is the plate number different? Also the offset appears to be fairly well inked, but there is nothing in the stamp area.



I thought that in "flat plate" printing, the same plate was used for each impression. When a change of the plate was necessary, the press was stopped, dismantled and the plate replaced. This would have allowed the impressions from the first plate to dry. If the plates were used sequentially. Plate 4983 would have been first.

I can imagine that a "separator" sheet (to separate the panes from different plates could have accounted for the lack of offset in the stamp area. There is a rather straight line at the top of this offset.

Any help would be appreciated! This may end up in an exhibit of strange thiggs involving stamps.

Thank you,