The Blazing World: Full of Amazing Stories

P. 361 tells how Edmund Halley calculated the total acreage of England at the close of the 17th century. He took the most recent map of England, cut it out and weighed it.  Then he cut out a circle at the center of the map and weighed it. The area of that circle adjusted by relative weights gave a pretty accurate total acreage. Yes, mountains works render this imprecise until you consider how few mountains England has