Arthur was a mariner who settled in Middletown Ct. about 1770. He appears in the 1790 census of Middletown with a household including three free white males over sixteen years, two free white males under sixteen, six free white females, and one slave (Heads of families at the first census of the United States in the year 1790. Baltimore : Genealogical Publishing Co., 1980, pg. 86).
Buried in Mortimer Cemetery, Middletown, Ct. In the latter years of his life, with Stephen Clay, they operated under the name Magill and Clay, engaged in the West Indies trade importing rum, molasses and other products of the islands. Their building was located on the east side of Main Street. later occupied by the Connecticut branch of the Bank of the United States, and still later by the Middlesex County Bank. (Frank Farnsworth Starr papers, Middlesex County Historical Society, Middletown, Ct).
World family tree # 5738 has birthplace as Tullycarne, Ireland.
Arthur accompanied his father to America, while his brothers John and Charles remained temporarily in Tullycarn with their sisters. Arthur was sympathetic to the colonies in their struggle with England. On April 4, 1777 he purchased what became known as "Magill Place" at No. 12 Ferry Street, near the river. The house had been built ten years earlier, and Arthur purchased it from its second owner, John Stocking, along with the Mansion House, barn, and all buildings for 1,000 Lbs Sterling. He apparently owned some 59,000 acres in Bryan County, Georgia (Ziebarth, John. Direct conections : Ziebarth-McGill ancestry. New York : Ziemag Publishing, 1997, pg. 82-85, 94).