Charles Steinmetz worked for General Electric for 31 years as a consulting engineer.

As the story goes, after retiring from GE, Steinmetz was hired back to help fix a malfunctioning machine.

After carefully inspecting the machine, testing various parts, looking thoughtfully here and there, he produced a piece of chalk from his shirt pocket and marked an "X" on a particular part. Later, after dismantling the machine, GE technicians were amazed to discover the flaw was exactly where Steinmetz had made his chalk mark.

They were almost as astounded when, several days later, Steinmetz sent them a bill for $10,000.

Seeking some sort of explanation from its long-time electrical guru, the company asked for an itemization of his bill. GE received this breakdown:
    For making one chalk mark on machinery:       $1.00
    For knowing where to put the chalk mark: $9,999.00