Google Offers US Patent Searching Back to 1790
Nancy Spitzer, Patents and Technical Reports Librarian at UW-Madison's Wendt Library, had this to say:
Patent librarians across the country are busily analyzing this new member of the Google family and it looks promising. There's much excitement because this is the first time that keyword searching of all US patents from 1790 to (almost) the present are available free on the Internet! (The US PTO Patent Full Text Database only allows keyword searching back to 1976 and Espacenet keyword in abstract back to 1920).
Google says: "We don't currently include patent applications, international patents, or U.S. patents issued over the last few months, but we look forward to expanding our coverage in the future."
Also, be aware of many glitches due to faulty OCR character recognition in older patents. "Electric EEEE CHIICFTE" was found to actually be "Electric cash register."
Please keep in mind that more precise, comprehensive, "advanced" patent searching is still going to require using the US PTO database and other resources.
Nancy also points out that there is no way to print or save the patents you find in Google. Fortunately, Nate Vack from Wendt has developed a script to add a link to the free pat2pdf service to any patent search result in Firefox.