THIS PROPOSAL SUPPORTS AN EFFORT AT GSFC TO RAISE THE BAND PASS CAPABILITIES OF PHOTOELECTRIC POLARIMETRY TO THE RANGE ACCESSIBLE FROM BALLOON FLIGHTS. BALLOON BORNE POLARIMETERY (IN THE BAND ABOVE 20 KEV) WOULD BE COMPLEMENTARY TO NASA'S CURRENTLY PLANNED IXPE SMALL EXPLORER AND WOULD HELP DETERMINE THE PROMISE AND FEASIBILITY OF A LARGER BROAD BAND WIDTH MISSION AFTER THE IXPE MISSION. MEASUREMENT OF THE HIGHER ENERGY POLARIZATION PROPERTIES OF THE XRAY EMISSION FROM PERSISTENT BLACK HOLE SOURCES CONTRIBUTES TO THE NASA THEME TO UNDERSTAND THE ORIGIN AND EVOLUTION OF THE UNIVERSE .