Prosper Cravath held the office listed for 1845 (register, county officers list).

The evidence

• “Storrs ; 1843, Ira Jones ; 1844, John L. Kimball ; 1845, Prosper Cravath ; 1846, Ira Jones ; 1847, Joseph CoUey ; 1848, Joseph Colley ; 1849, J. P.”

  1879-history-of-rock-county/10-rock-county-ch04-early-maps-courts-railroads.md, PDF p. 366 / book p. 370

  Butterfield, C. W., et al. The History of Rock County, Wisconsin: its early settlement, growth, development, resources, etc. Chicago: Western Historical Company, 1879. Cornell University Library via the Internet Archive, archive.org/details/cu31924028871585.

  Grade A: Found on a page of one of our sources