Supporting base for an electric fan
FIG. 1 is a front perspective view of a supporting base for an electric fan showing my new design; 
     FIG. 2 is a front elevational view thereof; 
     FIG. 3 is a rear elevational view thereof; 
     FIG. 4 is a top plan view thereof; 
     FIG. 5 is a bottom plan view thereof; 
     FIG. 6 is a left side elevational view thereof, the right side being a mirror image of that shown; and, 
     FIG. 7 is a right and top perspective view thereof, on a reduced scale shown in use. 
     The broken line showing of a fan, in FIG. 7, is for illustrative purposes only and forms no part of the claimed design.