Vintage black and white drawing of a hog. I’m not sure why the author identified this as a hog drawing as opposed to a pig or even a sow, but I do know that this illustration was drawn over 120 years ago and therefore is in the public domain.
Thomas E. Hill must have spent years writing his book Hill’s Album of Biography and Art. It was published in 1882 with hundreds of wonderful illustrations and what appear to be stock print foundry images. Over 200 of them can be found here on Reusable Art.
This image is copyright free and in the public domain anywhere that extends copyrights 70 years after death or at least 120 years after publication when the original illustrator is unknown.