Mike Walter seeks a catalogue of 13-1/2" Symphonion discs.  The Musical
Box Society of Great Britain maintains lists of many mechanical music
media on its web site.  The list for 13-1/2" Symphonion (we have it as
13-5/8") can be found here:

  http://www.mbsgb.org.uk/wp-content/uploads/2016/06/Symphonion13.pdf 

More information on these machines can be found in the Disc Musical Box
Book by Kevin McElhone:

  http://www.mbsgb.org.uk/product/the-disc-musical-box-book/ 

The book is also available from Nancy Fratti in the USA.

Best wishes from the UK,
John Farmer - Treasurer, MBSGB