400. That’s an error.

Google cannot redirect you to http://worldcat.org/search?q=Correspondence,+ed.+[W.S.+Taylor+J.H.+Pringle]+executors+his+son+John,+earl+Chatham+william+pitt+(1st+earl+chatham.) 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.