VIII. Duty, or the fireman's arithmetic

Coal cost money; the engines existed to save it. So the Cornish measured engines the way an owner would: foot-pounds of work delivered for every bushel of coal burned — the duty, printed monthly for all to see in Lean's Engine Reporter from 1811, engine against engine. It is the score in this museum too, and in the daily Trials. Note that duty counts coal burned, not coal used well: stoke beyond the engine's thirst and the surplus simply roars off at the safety valve.

One chapter of nine. Read the whole Primer, or work the engines themselves.