JPython library not found

I installed JPython 1.1, and then tried to follow the README.python for
running VisAD python scripts.  I typed

    java visad.python.JPythonFrame

as the readme instructed, and I get the message

    visad.VisADException: JPython library not found
 at visad.python.JPythonFrame.main(JPythonFrame.java, Compiled Code)

I noticed that JPythonEditor.java uses
org.python.util.PythonInterpreter, so I added the directory containing
the directory org/ to my CLASSPATH, but this didn't help.

-Neil