Sources

United States Patent Office, "Spirit Level," Patent No. 438,541, October 14, 1890.
United States Patent Office, "Spirit Level," Patent No. 449,609, March 31, 1891.
United States Patent Office, "Spirit Level," Patent No. 450,457, April 14, 1891.
United States Patent Office, "Incandescent Electric Lamp," Patent No. 475,394, May 24, 1892.
United States Patent Office, "Incandescent Electric Lamp," Patent No. 479,360, July 19, 1892.
United States Patent Office, "Incandescent Lamp," Patent No. 495,467, April 11, 1893.
United States Patent Office, "Incandescent Electric Lamp," Patent No. 510,018, December 5, 1893.
United States Patent Office, "Incandescent Lamp," Patent No. 547,249, October 1, 1895.
United States Patent Office, "Incandescent Lamp," Patent No. 553,673, January 28, 1896.
United States Patent Office, "Apparatus for Canceling Postal Marks," Patent No. 574,414, January 5, 1897.
United States Patent Office, "Advertising Device," Patent No. 576,266, February 2, 1897.
United States Patent Office, "Electric Searing Pen," Patent No. 597,373, January 11, 1898.
United States Patent Office, "X-Ray Apparatus," Patent No. 607,233, July 12, 1898.
United States Patent Office, "X-Ray Tube," Patent No. 958,488, May 17, 1910.
United States Patent Office, "Anode for X-ray Tubes," Patent No. 1,002,390, September 5, 1911.
United States Patent Office, "X-Ray Tube," Patent No. 1,042,109, October 22, 1912.
United States Patent Office, "Vacuum Tube," Patent No. 1,068,426, July 29, 1913.