Name the number of candidates for  samuel d. ingham
CREATE TABLE "table1_2668347_17" (
  "district" text,
  "incumbent" text,
  "party" text,
  "first_elected" real,
  "result" text,
  "candidates" text
);
SELECT COUNT("candidates") FROM "table1_2668347_17" WHERE "incumbent"='Samuel D. Ingham';