This solar sail patent http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=H... was educational to me (at some other site which showed the figures too) -- but it's literally the only time that's ever happened in my multi-decade career. It's written in a more helpful style than usual, and undoubtedly never saw commercial use in its lifetime. I would not have even looked if it were a patent in my own field.