Five and one half yards = Rod, Pole, or Perch
Four Poles = 1 Chain
10 Chains = 1 Furlong
8 Furlongs = 1 Mile
And also in horse-racing they have "Furlong-Poles" to mark the various distances (sometimes called 'pegs' . . e.g. "The Half-Mile Peg"
So quite correctly AB . .
40 Poles = 1 Furlong
Apropos of nothing at all really . .
Just a bit of nostalgia; the 'Good Old Days' etc