This thread looks helpful:

http://www.largeformatphotography.in...ad.php?t=72909

Note in particular threin the catalogue that Dan Fromm posted a link to:

http://www.collection-appareils.fr/a...9d3802b532215d

In particular, this page from that catalogue which seems to indicate that the lens was intended for 10cm x 15cm:

http://www.collection-appareils.fr/a...9d3802b532215d