The earliest known report of a trial of the Bloodhound's trailing abilities comes from the scientist Robert Boyle, who described how a Bloodhound tracked a man seven miles along a route frequented by people, and found him in an upstairs room of a house.With the rise of fox-hunting, the decline of deer-hunting, and the extinction of the wild boar, as well as a more settled state of society, the use of the Bloodhound diminished. A common misconception is that Bloodhounds are employed in packs; while this is sometimes the case in Britain, where foxhound blood is mixed into them to increase speed, in North America, Bloodhounds are used as solitary trackers. They are run over farm land by permission of the landowners. A line-walker (runner) is given a map, and sets off to follow a course marked on it, leaving a scent-article ('smeller') attached to a flag marking the beginning of the trail.