The Philly Cheesesteak is a sandwich principally of sliced pieces of steak placed on a lightly oiled griddle and chopped and flipped with a metal spatula until cooked to a light brown, then transferred to a long roll that is sliced lengthwise to form a cradle. Responsibility for the invention of the cheesesteak is claimed by Philadelphia's Olivieri brothers who began selling it at their hot dog stand near south Philadelphia's Italian Market in the 1930s. When was cheese added to the sandwich?
Back in the day
Radar is a means for detecting the position, movement, and nature of a remote object through radio waves reflected from its surface. It was developed (c.1935â€“40) independently in several countries as a military instrument for detecting aircraft and ships. One of the earliest practical radar systems was devised by Sir Robert Watson-Watt, a descendent of the inventor of the steam engine, James Watt. Radar contact was established with the planet Venus in what year?
Born on a day like today
Krupskaya was a Russian revolutionary and educator who was a Marxist agitator for 25 years before the Russian Revolution in 1917. She married Bolshevik founder Vladimir Lenin in 1898 when they were both in exile. After the Revolution, she joined the People's Commissar for Education and helped develop educational systems that offered both academic and professional training to women and workers. Her biography is known as the most detailed account of Lenin's life but omits what events?