Mica Alteration Research Articles

The Lighting of the Western World Fair

THE illumination of the San Francisco Panama-Pacific Exposition of 1915 set a high standard in exhibition lighting which was for long unsurpassed. According to an article on the Golden Gate Exposition, which appeared in the Electrician of January 20, it will be far surpassed by this new exhibition on Treasure Island in San Francisco Bay which will be opened on February 15. The gem-like appearance of the various buildings is mainly due to the use of an inexpensive insulating material called ‘’Vermiculite —an alteration of mica expanded by electric heat to fifteen to twenty times its original size. Applied to wet stucco, vermiculite imports an antique finish which scintillates with light. The sea wall and roadway lighting of Treasure Island is designed to be in keeping with the main project, and it is considered that it will establish a new milestone in the history of illumination. Projectors concealed in troughs floodlight the walls in white. Cylindrical golden amber lanterns are spaced on approximately sixty-foot centres along the entire facade for roadway illumination and to break up the flatness of the long lighted wall. Spectacular lighting has been arranged for the Courts of Paciflca and of the Seven Seas. The sculptured relief work consisting of submarine scenes is painted with paints that fluoresce under the ultraviolet light provided by concealed projectors from below. Nearly three hundred ultra-violet mercury floodlights, each of 100 watts capacity, are being used for fluorescence effects on outdoor murals. More £han two hundred underwater floodlights are being installed, and altogether the outdoor lighting equipment comprises more than 10,000 units. The interiors of exhibition buildings are uniformly lighted by day and night; they have no windows. At the high points of the main buildings a concentiated type of reflector is employed while at lowei points reflectors with layer spread are used. The total illumination of the 400 acre exposition site is estimated to require 40 million kilowatt hours during the 288 days the fair will be open.