William Helffricht (1807-1876) was born in Frankfurt, Germany, moved to Philadelphia in 1825, and was naturalized there in 1830. By the early 1830s he had gone into business on his own, advertising as "Mathematical, Optical, & Philosophical Instrument Maker At the old established stand of the late Wm. DAVENPORT, Sign of the Quadrant, No. 25, South Front Street." Helffricht remained at this address until 1848. A card in the wooden box holding the compass reads "Wm. Helffricht No. 25 South Street, Philadelphia."
This compass has a variation arc on the north arm that extends 25 degrees either way; the vernier reads to 5 minutes, and is moved by a rack and pinion under the south arm. There are two level vials on the south arm.
The compass was owned originally by Daniel Dunklin (1790-1844), who was elected governor of Missouri in 1832. Dunklin resigned the governorship in 1836, when Andrew Jackson named him surveyor-general of Missouri, Illinois, and Arkansas.
He probably bought the compass at this time, and used it to trace the boundary between Missouri and Arkansas, and to lay out numerous counties in these three states.
Ref: "Daniel Dunklin" in National Cyclopaedia of American Biography, vol. 12, p. 303.