December 25

1741: The Centigrade temperature scale was devised by astronomer Anders Celsius. 1776: General George Washington and his troops crossed the Delaware River for a surprise attack against Hessian forces at Trenton, NJ. 1868: Linus Yale, inventor and manufacturer of locks, including the cylinder or pin-tumbler lock known by his name, died.  1988: Ernst Ruska, an electrical engineer who invented the electron microscope, was born. 1939: "A Christmas Carol," by Charles Dickens, was read on CBS radio for the first time. 1966: St. Elmo Brady, the first black man to earn a PhD in chemistry, died. 1977: Silent films legend Charlie Chaplin died.