Ever visit the "Forevertron" in Wisconsin? One can argue whether the multicell horns were put to good use or it was just tragic, but I counted quite a few there.

But this might be of more interest:

http://www.audioheritage.org/vbulletin/showthread.php?33368-Any-one-know-about-the-Tar-filled-multi-cell-horns-1505-s