[6] He then studied law under Henry Brockholst Livingston, a future Associate Justice of the Supreme Court of the United States.
He soon built his practice in Manhattan into a lucrative business, which allowed him to take a house on Wall Street and to employ a married couple as his valet and housekeeper.
[4] He gained popularity in New York City's well-to-do social circles as a lawyer, Freemason, cavalry captain, and fire brigade inspector.
[4] For an unknown offense in 1798, which the historian Eric Henry Monkkonen interprets as an earlier duel or conflict, Eacker appeared in court and paid a recognizance, likely as a bond for good behavior.
[3] According to a supporter, the speech that Eacker delivered was commended by "nearly everybody" except for partisans who were "blinded... to every virtue" by "party spirit, which at that time was very bitter.
According to a 19th-century historian who relied on Eacker's younger brother as a source, the speech was entirely patriotic and did not name or allude to Hamilton.
[3] According to Eacker's brother, the prolonged illness began in January 1802 on a bitterly cold night when Eacker fought a raging fire with his brigade and contracted a severe cold that "settled upon his lungs" until his death.
In January 1808, Harriet Livingston married the steamboat inventor Robert Fulton with whom she had four children.