The differences between the engraving and the photograph are very telling. In the QM photograph the cavalryman wears his carbine slung on the left side. Cavalrymen always wore their carbine sling as it appears in the engraving (carbine on the right or off side). The artist or his editor appear to have corrected the error appearing in the QM (Quartermaster) photograph. Those taking the QM photographs may have been more interested in the equipage than correct manner of wear or may not have been familiar with cavalry practices. In the QM photo his Spencer carbine can be seen while in the engraving it is behind him.
The Quartermaster Department requested an appropriation of Congress to produce images documenting the regulation uniform of the Civil War. This shows a great deal of vision on the part of those who advanced the idea at the time and the collection of images provides a wealth of information for those studying uniforms of the period. The oblivious problem with the collection is that it does not reflect the true appearance of soldiers in the field. A model was dressed in various uniforms from the depot stock. It is possible that some of the images may even not picture totally correct regulation dress.