On May 4, 1852, U.S. Patent No. 341,214 issued to C. Bell and Charles Sumner Tainter on Recording and Reproducing Speech and Other Sounds (the disc-shaped record).
On May 3, 1966, U.S. Patent No. 3,249,473 issued to Nick Holonyak, Jr., on the Use of Metallic Halide as a carrier Ga in the Vapor Deposition of III-V Compounds (making LED’s in the visible light spectrum).
On April 30, 1912, U.S. Patent No. 1,025,075 issued to Frank J. Schumann on a Vending-Machine, adapted for postage stamps or tickets — and yet we still wait on long lines to buy both.
On April 26, 1966, U.S. Patent No. 3,248,705 issued to James E Dammann and Edward J. Skiko, on an Automatic Editor — one of the first word processing systems.
On April 25, 1950, Erwin J. Schweitzer and Carmine Jordan received U.S. Patent No. 2,505,652 on the Tail Wheel Actuated Arresting Hook — that automatically deployed the tail hook with the landing gear to facilitate landing on an aircraft carrier.
On April 23, 1907, U.S. Patent No. 850978 issued to Ignatius Soares on a Nose Shaper. Fortunately for plastic surgeons everywhere, Ignatius’ invention never caught on, because the user sure looks delighted.
On April 22, 1879, U.S. Patent No. 214,663 issued to William L Hunt on Improvement in Theater Appliances — the appliance in question being a human cannon.