An obscure research beacon

This month's "Genealogy Gems" from the Allen County Public Library in Fort Wayne (not yet archived here) includes a note by Delia Cothrun Bourne about NARA publication M1373, "Registers of Lighthouse Keepers, 1845-1912," nineteen rolls of microfilm complete with maps and indexes. The Great Lakes have two of the six rolls, 1845-1900 and 1901-1912.