In 1887 Mr. Felt was issued a patent for his invention from the United States Patent & Trademark Office (USPTO). There were 10 documents on file for this patent. The drawing specification sheet of the patent has been reproduced from original USPTO documents and printed onto parchment paper. This print is sized and ready to install into an 8" x 10" frame. The additional sheets included are printed on 5.50" x 8.50" parchment paper. These accompanying documents describe the scope of this invention in formal terms. The following is an actual excerpt from the patent…

       " To properly define the position of this invention in the art, I desire to say that machines of this order may be conveniently divided into two classes-viz., counting-machines and calculating- machines. I call counting-machines those wherein a series of numeral wheels are actuated by impulses or strokes delivered to the first or units wheel and periodically transmitted to the succeeding wheels of the series by carrying mechanism, so that at the completion of the tenth step of one wheel the wheel of the next higher order will be caused to advance one step. Each wheel being numbered from 1 to 10, the quantities indicated proceed in decimal order."…