At the beginning of the 20th century Henry Ford’s electrical engineers had issues they could not solve with a gigantic generator. Henry Ford called Steimmetz, a genius mathematician working for GE to help them.
When he arrive at the factory he spent 2 days and night listening to the generator and scribbling on his notebook.
After that he asked for a ladder, climbed on it, put a chalk mark on a specific spot and explain to the engineers that they needed to remove the plate and replace sixteen windings behind the plate. After that the generator worked perfectly and Ford received a $10 000 bill.
Ford asked for an itemized bill and Steinmetz sent this