In a message dated 98-03-26 09:52:27 EST, you write:
 
<< I am trying to date an early water sprinkler system.  Water filled,
 teardrop-shaped leaded glass globes are placed on a beam in the
 attic.  A thin strip of copper wire is coiled around the neck of each
 globe which, in the event of a fire, would heat to such a degree that
 the glass would shatter and (theoretically) the water would then
 extinguish the fire. >>
 
I can only offer an anecdote, in that I grew up in a house built in the 1940's
with a similar set of globes near the gas furnace and water heater.  We were
told in the 1970's that these were filled with some kind of fire retardant
chemical rather than water, which makes sense given that the things held only
about 12 ounces or so.
 
           Larry McKee