Hi All

We have been monitoring cleanup activities at an old Navy base near San
Francisco.  Yesterday two masts sections were exposed.  Both are made of steel and
are about 17 feet long but don't appear to articulate.  The sections have a
16-inch-square outer shell that surrounds an 11-inch-square core.  Metal ladder
rungs extend up one (aft?) side.  The  crow's nests are D shaped in plan with
the mast passing through the "D" adjacent to the flat side.  The nest is six
feet from side to side with a three foot radious.  An inverted cone shaped
support extends below the crow's nest and intersects the mast about two feet below
the floor of the nest.  The floor is gone but I assume it was wood?

Does anyone know when the military began using steel masts and D shaped
crow's nests?  The base operated from the 1850s until 1990s.  The very few
artifacts found around the mast appear to be post 1900.  THe mast was found in a part
of the base that used to be bay but was filled in the 1930s-early 1940s in
anticipation of World War II buildup.

Thanks in advance for the wonderful help Histarch-ers are prone to give

Mary Maniery
PAR Environmental Services