It is my understanding, from the edition of the 'A' volume of this
encyclopedia published by the fine folks over at Project Gutenburg,
that it is "uncool" to use the name "Britannica" in association with
this book. The reason is that although the _copyright_ has indeed
properly expired, the _trademark_ is still that of an active company.
So, while the text is fair game, the name is not.
I'm cc:'ing this message to editor(a)1911encyclopedia.org, just so that
person will know about this. But my opinion is not very
authoritative. I'd just suggest getting the word 'Britannica' off the
site _in the logo_, while feeling free to use the word in a text
explanation of where this information comes from. (My understanding
is that it's o.k. to say a trademark in just about any context, but
not o.k. to use it in a fashion that might mislead people into
thinking that you are the organization in question.)
The site, as it stands, doesn't really make clear that the people
behind it are not the official Britannica people.
What a wonderful thing to have online.
--Jimbo