The Collaborative International Dictionary of English v.0.48:

deckle \dec"kle\ (d[e^]k"k'l), n. [Cf. G. deckel cover, lid.]
   (Paper Making)
   A separate thin wooden frame used to form the border of a
   hand mold, or a curb of India rubber or other material which
   rests on, and forms the edge of, the mold in a paper machine
   and determines the width of the paper. [Spelt also deckel,
   and dekle.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Deckel \Deck"el\, n. (Paper Making)
   Same as Deckle.
   [1913 Webster]