Does anyone know the author of the supplement portion of the following item, published in 1822: 

A letter to the Honorable Brockholst Livingston, esq., one of the justices of the Supreme court of the United States, on the lake canal policy of the state of New-York ... By Robert Troup, esq. With a supplement, and additional documents.

I have some reason to believe that the supplement, which is longer (and considerably more interesting) than the main item, was written by future US Attorney General Benjamin F. Butler (1795-1858); in 1822, he was the Albany law partner of Martin van Buren and a devoted opponent of canal-maker DeWitt Clinton.  

Gerard Koeppel
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www.gerardkoeppel.com