Noun
A drum.
A panel; a tympanum.
A frame covered with parchment or cloth, on which the blank sheets are put, in order to be laid on the form to be impressed.
Source: Webster's dictionaryThen the screw is reversed, the windlass turned again to move the bed back to its original position, the tympan and frisket raised and opened, and the printed sheet removed. Source: Internet
The paper is now held between a frisket and tympan (two frames covered with paper or parchment). Source: Internet
One damp piece of paper was then taken from a heap of paper and placed on the tympan. Source: Internet