1. B.C. Tilghman, U.S. Patent No. 108,408, October 18, 1870.
2. B.C. Tilghman, U,K. Patent No. 2,900, November 3, 1870.
3. B.C. Tilghman, U.K. Patent No. 3,626, December 2, 1872.
4. J.E. Mathewson, U.K. Patent No. 1,584, April 23, 1877.
5. J.E. Mathewson, U.K. Patent No. 12,306, January 13, 1894.