Washington's Will Had ADR Clause

From this post from Death and Taxes - The Blog:

George Washington's Will included an ADR provision...as follows:

But having endeavoured to be plain, and explicit in all Devises--even at the expence of prolixity, perhaps of tautology, I hope, and trust, that no disputes will arise concerning them; but if, contrary to expectation, the case should be otherwise from the want of legal expression, or the usual technical terms, or because too much or too little has been said on any of the Devises to be consonant with law, My Will and direction expressly is, that all disputes (if unhappily any should arise) shall be decided by three impartial and intelligent men, known for their probity and good understanding; two to be chosen by the disputants--each having the choice of one--and the third by those two. Which three men thus chosen, shall, unfettered by Law, or legal constructions, declare their sense of the Testators intention; and such decision is, to all intents and purposes to be as binding on the Parties as if it had been given in the Supreme Court of the United States.