Willy H. Welcker - South San Francisco CA
A double helical earthquake and fire escape structure for multiple story buildings formed mainly of a plurality of prefabricated section of precast concrete. Two identically formed upper sectional units and two identically formed lower units are arranged in facing relationship to each other for each floor of the building. Complementary portions of the assembled units combine to form a pair of oppositely disposed entrances on each floor leading to two separate helical slides arranged about a separately formed central circular smokestack. The units are provided with steel members adjacent their edges which are connected together and secured to a surrounding supporting steel framework. Two additional smokestacks formed within the corners of the assembled units may also be used as shoe drops.