Who was the author of amendment 4 and 15?

Congressman John A. Bingham of Ohio was the primary author of the 14th amendment, with Senator Jacob Howard of Michigan contributing.

John Bingham was the primary author of the 15th amendment as well, but it was based largely on previous proposals by Congressman George Boutwell of Massachusetts and Senators William Stewart of Nevada and Henry Wilson of Massachusetts.

EDIT: BAM! The good Reverend has it. You go, Grape!!

Amendments 4 and 15 are about 80 years apart so I have to assume you meant 14 and 15?

Article 14:

Section 1 Right to citizenship, civil rights, due process, and equal protection under the law.

Section 2 Apportionment of Representatives.

Section 3 Particpation in rebellion.

Section 4 Validity of public debt.

Section 5 Power of enforcement.(proposed in 1866 and ratified in 1868)

John M. Howard, Senator from Michigan, wrote one of the clauses for the 14th Amendment, the citizenship clause.

Article 15: right to vote regardless of race

One way for amendments to come into being is for the Congress propse it, with the House of Representatives and the Senate submitting proposed wording.

So the 14th and 15th Amendment of the Constitution was proposed by the Thirty-ninth Congress of the United States, and would therefore be the author of the amendment.