The Mechanics of Weathervanes:
Weathervanes are as old as our fascination with wind and were one of the
first meteorological instruments. Weathervanes work because of their pivoted
construction: the ornament has a socket that attaches to a spindle. In order for
it to catch the wind properly, the back section of the ornament should have a
larger area than the front section, but the front section must weight the same
as the back. The front section of the weathervane points into the wind,
indicating from which direction the wind is blowing.