After participating in derby car races, William wondered if any of the lubricants used on the cars' wheels might reduce friction more than other lubricants. He hypothesized that dry lubricants, such as graphite, would work better than liquid lubricants, such as motor oil.
William mounted a single wheel on an axle. He designed a machine to spin the wheel, then allow it to rotate freely. He applied five lubricants individually to the connection between the wheel and axle, then tested how many turns the wheel made while it was spinning freely. William found that graphite gave the wheel the greatest number of spins, followed by graphite with molybdenum, silicon, motor oil, and white Teflon.
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