The clock could tell the correct time in two places, meeting the requirements for learning longitude on the sea.

VOA: special.2010.07.14

Then he had to seek the correct information in the Nautical Almanac about the moon and stars at that time of night or day.

VOA: special.2010.07.14

And time has proven him correct. Bill Gates was Microsoft's largest shareholder.

VOA: special.2011.01.07

The first three are still operating, showing the correct time.

VOA: special.2010.07.14