c. 1860's H. G. Kern Trepanning Set

Horatio G. Kern, was in the surgical instrument business in Philadelphia from 1837 to 1893.  He was a contract supplier of instruments to the Union Army during the Civil War.  During the 1860's his location was at 25 N. 6th in Philadelphia, Pa. (from Edmonson; American Surgical Instruments: an Illustrated History):

Horatio G. Kern surgical instrument maker

1837: Filbert St. bel. 8th

1838-42: 7 N. 8th

1843-48: 5 N. 8th

1849-59: 293 High

1860-70: 25 N. 6th

1871-89: 21 N. 6th (joined by Horatio G. Kern, Jr., in 1876; Horatio G. Kern, Sr., dies in 1889)

1890-92: 122 S. 12th surgical instruments

The rosewood case, with brass corners measures: 5 5/8 x 9 5/8 x 1 1/2 inches.   The center lock has been broken.  Apparently someone lost the key and didn't know how to open the lock other than by force.  This was a civilian set as evidenced by the central keyed lock.

The set was dated by comparison of instruments to other existing sets of the period.  The presence of two trephine handles is unique compared to other trepanning sets in this collection.