CREATE TABLE table_55415 ("Edition" CLOB, "Round" CLOB, "Date" CLOB, "Surface" CLOB, "Opponent" CLOB, "Result" CLOB)

On July 15, 1984 what surface was used?
SELECT "Surface" FROM table_55415 WHERE "Date" = 'july 15, 1984'
SELECT "Surface" FROM "table_55415" WHERE "Date" = 'july 15, 1984'