"Augustus Platt, son of Benjamin Platt and Adah Fairchild, was born in New York August 4, 1793.  He died February 28, 1886 in Columbus, Ohio.  He is buried in Greenlawn Cemetery. His son, William Augustus was born in Lanesboro, Massachusetts in 1809.  He is said to have moved to Columbus, Ohio with his grandfather, Benjamin, about 1817.  The first directory of Columbus issued in 1843 lists as a mathematical instrument maker:  Platt, Augustus (Platt & Son).  The son was Calvin Platt.  In 1862, Calvin was superintendent of another company.  Augustus Platt is listed as a mathematical instrument maker until 1872."

Reference:  Smart, Charles E.   The Makers Of Surveying Instruments In America Since 1700  Troy, New York:  Regal Art Press.  1962