Richard, you've pretty much answered your own question. This is a woodcut which came out of the Harper's Weekly newspaper. The value on these woodcuts tend to range from $30-$50. Some of the earlier ones and an 1869 woodcut depicting the Red Stockings tend to go for a premium. This is one of the earlier ones but the more valuable ones tend to be from Frank Leslie's Illustrated. There are also some very obscure publications which contain some beautiful woodcuts but not well documented.
http://www.oldcardboard.com/n/harper...?cardsetID=679