Earth and Space Science: Patent Search Engines

Publication coverage: 1836 - Present.
Espacenet is free to use and allows PDF downloads of patent documents. The database includes 60 million patent documents from over 70 countries.

Canadian patent records, 1869 to present; full-text documents, 1920 to present.
CIPO allows you to access 93 years of patent descriptions and images and search, retrieve and study more than 2,140,000 patent documents.

U.S. patents, 1790 to present; Published applications, 2001 to present.
Search for download patents for free. Patents before 1976 can be retrieved by number, date and classification. A TIFF viewer is required to view/print patent documents.

International patent applications: 1978 to present.
Here you can search 30 million patent documents including 2.2 million published international patent applications (PCT).

AU, EP, US and WO patent documents: 1970s to present.
Patent Lens is a free public resource of searchable patents worldwide.

Google patents includes patents submitted either in the U.S. or European Patents Offices. You can search, read, and view patents using Art Finder.