Arnold & Co. Philadelphia			F. Arnold & Co. Chicago, Ill. Instrument shown is from the collection of the National Museum of American History, a division of the Smithsonian Institution

 

Francis Arnold's naturalization petition dated May 4, 1854, renounced allegiance to the free city of Frankfurt.  He is listed in the 1855 Philadelphia City Directory as a Math Inst Maker at 33 N. 7th Street.  This was the address of  William J. Young's establishment, so it is assumed that Arnold worked for Young at the time.  Francis Arnold was naturalized in Philadelphia in 1856.  An advertisement in the the 1857 Philadelphia City Directory reads:  "Arnold & Co. Manufacturers of Surveying Instruments, Levels, Transits, Compasses, &c.  Patent Models after or with drawings.  We call the attention of Astronomers, Surveyors and Students to our new constructed Microscopes & Telescopes.  74 S. 3rd" 

From 1861 to 1865 he is listed in the Chicago City Directories as a math inst mkr.  In 1866 he is listed with Bruno Kraatzenstien as F. Arnold & Co.