Adding Machine, 1642. Inventor: Blaise Pascal (France) (1623-62). Earliest commercial machine invented by William Burroughs (USA) in St. Louis, Missouri in 1885.

Addressograph, 1893. Inventor: J.S. Duncan (USA). Manufactured in Chicago, Illinois.

Aeroplane, 1903. Inventors: Orville Wright (1871-1948) and Wilbur Wright (1867-1912), (USA) Kitty Hawk, North Carolina.

Airship (non-rigid), 1852. Inventor: Henri Giffard (France) (1825-82).

Steam-powered propeller flew over Paris (1852).

Airship (rigid), 1900. Inventor: Graf Ferdinand von Zeppelin (Germany) (1838-1917). Bodensee.

Antiseptic, 1867. Inventor : Dr. Joseph lister (England).

Arc Lamp, 1879. Inventor: C.F. Brush (USA) (1849-1929). Cleveland, Ohio.

Argon, 1894. Inventor: Sir William Ramsay and Baron Ray Leigh (Great Britain).

Aspirin, 1899. Inventor : Dr. Felix Hoffman, Germany.

Atom (Nuclear Model), 1911. Inventor: Ernest Rutherford, (1871- 1937) England.

Atom Bomb, 1945. Inventor : Julius Robert Oppenheimer (USA) (1904- 1967).

Atomic Theory (ancient) :
Leucippus Democritus (Greece) (500 BC).

Atomic Theory (modem) : John Dalton (England) (1808).

Autogiro, 1923. Inventor: Juan de la Cierva (Spain) (1896-1963). Horizontal unpowered rotor.

Automobile (steam), c. 1769. Inventor: Nicolas Cugnot (France) (1725- 1804). Three-wheeled military tractor. Oldest surviving is Italian Bordino (1854) in Turin.  

  Automobile (gasoline), 1855. Inventor: Karl Benz (Germany) (1844- 1929). Earliest model by Father Ferdinand Verbiest (d. 1687) c. 1665 in China. Earliest internal combustion automobile built (1862-63) by Jean Joseph Etienne Lenior (1822-1900) (France). First run by Benz Motorwagon, Manneheim in November or December 1885. Patented in January 29,1886. First powered handcart with internal combustion engine was by Siegfried Marcus (Austria) (c. 1864).