This set is by Kern, Philadelphia. It is a fascinating set and somewhat of a mystery. It is a 4 layer set incorporating instruments for neurosurgery, general amputation and orthopedics. Considering that there are 4 layers and this is a large set size-wise it is interesting that there are relatively few instruments. Some minor pieces such as scalpels are missing but the majority of instruments are there, including the unusual rongeur's for picking at bone during and amputation. 

This set is very similar to the Kolbe set on this site. They both have slide latches common to military sets and both are from Philadelphia. The layouts of the sets are similar as well. None of the instruments in this set are stamped USA Hosp Dept, though. Interestingly, this set has an original sales receipt with it, in fancy script, stating that the set was sold on August 9, 1865 to Benjamin Pope. Some research revealed that Pope was an Assistant surgeon with the New York 10th heavy artillery during the war. He was mustered in upstate New York and mustered out a few months prior to the date of sale on the set in Washington. The set was sold in Washington therefore making it likely a set he used as a civilian surgeon after the war. 

Most likely this was a set originally intended for military use but then sold to a civilian as an "extra" towards the wars end. There were many such sets. When I got this set it was apparent that the nameplate was reversed. I removed it and on the other side was inscribed "Adams." That deepens the mystery. . . could it have been sold to Adams after it was owned by Pope? Research is ongoing.

Addendum!!: Turns out that Pope was in the 6th AND 10th NY heavy artillery. He was in the 6th just before being mustered out. The chief surgeon of the 6th was one John Adams. The picture now comes together: Most likely Pope got the set from Adams on the 6th, and after being mustered out did what other surgeons did: bought the set back from the government. Of course, he wouldn't want Adams name on the top of the case so he flipped the plate and voila. . . . the mystery is solved (or so I think).