Scientific American 12, 11.12.1847
By Charles W. Roberts, and John Hambly, of Philadelphia, Pa. Improvement in machinery for Rasping Dye Woods. Patented 21st August 1847. Claim. - Having thus fully described the construction and operation of our improved machine for rasping dye woods, roots, bark, &c, into powder. What we claim therein as new and desire to secure by Letters Patent is the construction of the rasping wheel of a series of parallel circular saws, secured to the shaft in an oblique position thereto, so that their rasping action will operate on the wood to the right during one half the revolution, substantially, in the manner and for the purpose herein set forth.