On April 18, 1911, U.S. Patent No. 990,191 issued to Carl Bosch, Ph.D. on a Process of Producing Ammonia.

On April 17, 1973, U.S. Patent No. 3,728,480 issued to Ralph H. Baer on a Television Gaming and Training Apparatus.  This product was marketed as the Magnavox Odyssey in 1972-1975.

On April 16, 1935, U.S. Patent No. 1,997,901 issued to Orton H. Englehart on a Water Sprinkler — the familiar rotary impact sprinkler.

On April 15, 1952, U.S. Patent No. 2,592,927 issue to Howard Manning on Adjustable Pliers — channel lock pliers.

On April 14, 1896, U.S. Patent No. 558,393 issued to John Harvey Kellogg on Flaked Cereals and Process of Preparing Same.

On April 13, 1869, U.S. Patent No. 88,929 issued to George Westinghouse, Jr., on a Steam Power Brake.

On April 12,1966, U.S. Patent No. 3,245,800 issued to Harlan Sanders on a Process of Producing Fried Chicken Under Pressure, but we still don’t know his secret recipe of herbs and spices.

On April 11, 1893, U.S. Patent No. 495,341 issued to Frederick E. Ives on a Photogravure Printing Plate.

On April 10, 1849, U.S. Patent No. 6281 issued to William Hunt on a pin – the first safety pin.

On April 9, 2002, U.S. Patent No. 6,368,277, to Steven Olson on a Method of Swinging on a Swing.

Unfortunately for young Mr. Olson, the Commissioner ordered reexamination of his patent, and the claims were found to be unpatentable.