Cunning

lubrication system on an early gas engine. Two drops per revolution, carried up from the oil bath on a short wick and then dropped into the central tube as the wick touches the little bar. 

A happy return visit to the Hereford Waterworks Museum, with a bonus from the Hereford Society of Model Engineers. 

Five years ago: https://www.blipfoto.com/entry/4655333