Which Driver has a Date of 16th september 1951, and a Race of dns?
CREATE TABLE "formula_one_entries_for_brm_type_15" (
  "date" text,
  "event" text,
  "circuit" text,
  "driver" text,
  "race" text
);
SELECT "driver" FROM "formula_one_entries_for_brm_type_15" WHERE "date"='16th september 1951' AND "race"='dns';