Knowledge Zone#OnThisDay Samuel Colt patented the first production-model revolver, the .34-caliber (1836).
George Westinghouse patented the air #Brake (1868).
The #ZX81, a pioneering British home #Computer, was launched by Sinclair Research (1981).
Birth Anniversary of Gerardus Mercator (1512) - most renowned for creating the 1569 world map based on a new projection.
