F. Arnold Surveyor's Vernier Compass

This is an incomplete example (the arms are missing) of an unusual 4–armed instrument. The needle rim is graduated to 30 minutes. The variation scale, at south, extends ± 20 degrees, and is read by vernier to single minutes. The “F. Arnold & Co.” inscription refers to Francis Arnold, an immigrant from Frankfurt, Germany, who signed naturalization papers in Philadelphia in 1854. After apprenticing briefly for William J. Young, Arnold went into business on his own, advertising as a manufacturer of surveying and engineering instruments. He first set up shop in Philadelphia in 1855 at 33 N.7th St. and in 1857 at 398 S. Front St. 

He eventually settled in Chicago around 1860. By 1875, B. Kratzenstein was advertising as Successor to F. Arnold & Co.

Natural History Museum