Meghan, it seems like one thing you could do, following from what John
said, would be:
Physics--Societies, etc.--History

Or if the departments were in a particular geographical area, the US,
for example, it could be:
Physics--United States--Societies, etc.--History

That is on analogy with this string in LC's catalogue:
Accounting |z United States |x Societies, etc. |x History.

That requires the user (including the reference librarian) to
familiarize herself with "Societies, etc." as including such things as
academic institutions. That may seem rather arbitrary, but it's a common
problem with controlled vocabulary. And that's what reference librarians
are for, to guide patrons through those mysteries.

Ted Gemberling
UAB Lister Hill Library
(205)934-2461