400. That’s an error.
Google cannot redirect you to http://worldcat.org/search?q=Code+diplomatique,+contenant+les+traités+conclus+avec+République+française,+1792+jusqu'+à+1802,+par+Portiez+france+treaties because the request was invalid.
This might be because the link was created a long time ago. Try your search again on Google. That’s all we know.