Misc: What is the 'bishop's stone'?

Questions

This Pope was murdered by an irate hubby who found him on top of his wife?

How many umbrellas are lost on the London Underground each year?

Until the introduction of the Julian Calender in 1752, New Year's Day fell on which date?

Which country is the only one which doesnt print its name on its postage stamps?

Where is it illegal to cross state lines with a duck on your head?