Graybeard Blackpowder forum member "Steelcharge" has turned up more goodies, and posted them on that forum. One of the more interesting series are the 33 pages, 292 images, of antique cannon models in French museums, primarily in the Invalides in Paris. Some of the models are quite incredible, and some represent artillery concepts I've never seen before, such as a cannon and mortar cast as one piece.
http://www.photo.rmn.fr/cf/htm/CSear...6&New=T&Page=1