An attempt to find patterns of social connection between people by asking them to forward a letter to a named person.  Participants passed the letters on to others known to them bearing geographic, familial or professional proximity to the addressee.  It lead to the conclusion of a six degree separation between two strangers. This experiment reconfirmed the sociometry of Jacob Moreno in the 1930s and subtends social network analysis today.  Its significance is that: 1) it conflates human relations with communication channels, postal in the experiment, and internet in today's context; 2) it shows that there is a pattern one can follow to understand social relations, and by which people can predict and engineer certain social phenomenon.