Carriage Waywiser, by Ramsden, London, Late 18th Century

Brass with silvered dial calibrated with two scales: 0-31 by eighths and 0-100 by ones; and iron hands; the whole in a mahogany case with hinged lid on the inside of which is glued a paper manuscript table of calibrations made in 1903 and 1807. The instrument is clipped to a carriage by three key-hole slots in the back; the drive is to a tapered, square-sectioned shaft at the bottom.