The traditional British units of length or distance have been based on two standard lengths: the barleycorn (the length of a grain of barley) and the yard (the length of an arm, or sometimes defined as from the tip of the nose to the tip of the finger when an arm is outstretched). Other units have generally been defined in terms of those, though the perch or rod, as it was also known, had originally been defined as the total length of the left feet of the first sixteen men to leave church on Sunday morning, and the average length of those feet became the foot.