Franklin planned to observe an eclipse of the
moon, but a noreaster storm blew into Philadelphia and obstructed
his view. Later, he discovered that people in Boston, hundreds of
miles away were able to view the eclipse before the storm arrived.
Franklin correctly theorized that the direction of the prevailing
wind is not necessarily the direction of the storms movement.
This is the first known instance in which the movement of a storm
system as a whole was recognized.