Online Encyclopedia of Western Signs and Ideograms Symbols.com

Symbol 39:1

3901

39:1 · The upward pointing triangle to denote the element of fire in alchemy during the Middle Ages became the hot and humid element of air with a horizontal bar added across it. The air element was also drawn 2204b and 1006.
    This sign has in modern times been used as a meteorological sign for frozen drizzle, corn snow.
    As a sign in the French hobo or gypsy system 3901 means the master of the house has just died.