Initiative measure adding Section 15 to Article XIII of Constitution. Declares all property owned, operated, managed or controlled by any municipality, county, district or other public agency, created and existing under laws of California, and held or used for supplying the public with light, power, heat, transportation, telegraph or telephone service, shall be assessed and taxed in same manner, to same extent and for same purposes, as like property held or used for like purposes by private corporations and natural persons shall be assessed and taxed under the State Constitution and laws