From the Descendants of Robert Doig of Scotland site.
He was engineer on the USS Mercedita in its battle with the CSS Palmetto State in 1863 which I wrote about recently. The ship was commanded by Henry Stellwagen.
ALEXANDER THOMAS DOIG was born 4 December 1821 in Of Dundee, Angus, Scotland. Died 16 April 1869 at 406 Hicks Street in Brooklyn, New York and buried at Green-Wood Cemetery in Brooklyn.
In 1841, he was an engineer living on Milton Street in West Derby. In 1844, he was living in Montreal and then emigrated to New York state about 1846.
The June 29, 861, issue of "Scientific American" mentions an A. Doig, an engineer, who developed a new refrigerated journal (bearing) box for steamship application.. The signature on the patent confirms it was Alexander Doig.