400. That’s an error.

Google cannot redirect you to http://worldcat.org/search?q=London+encyclopaedia,+or,+Universal+dictionary+science,+art,+literature,+practical+mechanics,+orig.+ed.+Encyclopaedia+metropolitana+[T.+Curtis].+thomas+curtis+(of+grove+house+sch+islington) 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.