Source : Webster's Revised Unabridged Dictionary (1913)

Hammercloth \Ham"mer*cloth`\ (?; 115), n. [Prob. fr. D. hemel
   heaven, canopy, tester (akin to G. himmel, and perh. also to
   E. heaven) + E. cloth; or perh. a corruption of hamper
   cloth.]
   The cloth which covers a coach box.