EDIT: In case anyone wants to make me feel bad about pirating, Jaynes is dead, and besides that, I bought a hardcopy as backup.
http://www.naturalthinker.net/trl/texts/Science/Jaynes,%20E....
The first couple pages are a bit funny looking, but after that, there are all 500+ pages. It was the fourth result on Google for me.
EDIT: In case anyone wants to make me feel bad about pirating, Jaynes is dead, and besides that, I bought a hardcopy as backup.