One of our team then related the story of a Boiler “tapper” in 17^th century Scotland.  To make a major repair to an industrial boiler in those days it first had to be drained through a drilled hole, a process called “tapping.” It was important that the person who did the “tapping” had to be an expert or the boiler could be ruined and forever unusable. One famous 75-year old Boiler “tapper” completed his work at a factory with consummate skill to the customers delighted satisfaction.  He forwarded his bill for payment that succinctly described the skill he had acquired over a lifetime.  It simply said  “For tapping” boiler – one pound. For knowing where to ‘tap’ boiler 100 pounds.”