The complete photo is at the Library of Congress Online, and is part of their Civil War Photograph collection.
TITLE/LABEL Unknown location. 12-pdr. Napoleon (model 1857?)
PHOTOGRAPHER not specified.
CREATED/PUBLISHED Between 1860 and 1865.
MEDIUM 1 negative (2 plates) : glass, stereograph, wet collodion.
REPOSITORY Library of Congress Prints and Photographs Division Washington, D.C. 20540 USA
CALL NUMBER LC-B811- 2582
REPRODUCTION NUMBER LC-DIG-cwpb-01981 DLC (b&w copy scan of left half)
LC-DIG-cwpb-01980 DLC (b&w copy scan of right half)
LC-B8171-2582 DLC (b&w film neg.)
COLLECTION Selected Civil War photographs, 1861-1865 (Library of Congress)
DIGITAL ID (b&w copy scan of left half) cwpb 01981 http://hdl.loc.gov/loc.pnp/cwpb.01981
(b&w copy scan of right half) wpb 01980 http://hdl.loc.gov/loc.pnp/cwpb.01980
(intermediary roll film) cwp 4a39730
NOTES Civil War photographs, 1861-1865 compiled by Hirst D. Milhollen and Donald H. Mugridge, Washington, D.C. Library of Congress, 1977. No. 0145.
Photographs of artillery, place and date unknown.