There are 43,560 square feet in an acre. This is equal to 1/640 of a square mile, or approximately 80 percent of the area of an American football field, including the end zones.
Kirkby is a name that was brought to England by the ancestors of the Kirkby family when they migrated to the region after the Norman Conquest in 1066. The Kirkby family lived at Kirkby in Furness. The name Kirkby means village with a church.
One possibility is the earliest use of the term, which originates from the Viking town law in the Danelaw, wherein by is the Old Norse word for a larger settlement as in Whitby and Derby (compare with the modern Danish-Norwegian word by meaning town, or the modern Swedish word by, meaning village).