Who was the incumbent when the candidates were John banks (am) 52.2% samuel power (j) 47.8%?
CREATE TABLE "pennsylvania" (
  "district" text,
  "incumbent" text,
  "party" text,
  "first_elected" text,
  "result" text,
  "candidates" text
);
SELECT "incumbent" FROM "pennsylvania" WHERE "candidates"='John Banks (AM) 52.2% Samuel Power (J) 47.8%';