"John Roach was born in Cork, Ireland in 1813.  He is first listed in the New York City directories in the 1833-34 edition as "philosophical instrument maker".  In 1841-42 he is listed as Roach & Warner, instrument makers; with Henry Warner as his partner.  From 1843 to 1855 he is variously listed as an optician and maker of surveying instruments.  He moved to California in approximately 1855 and is listed in the San Francisco directories from 1858 to 1891.  He died in San Francisco in 1891."

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