World History for the years :-

• 1700 - 1799 Go back 100 years
  
  
• 1800 Turn of the new century.
  
  
• 1837 The Georgian period came to an end.
  
  
• 1880 William Joseph Hammer (in charge of testing early light bulbs), noticed a blue glow around the positive wire in a vacuum tube and a blackening of the bulb at the negative wire. By introducing a metal plate at the top of the bulb, he invented the diode valve.
  
  
• 1900 - 1999 Go forward 100 years