[Magdalen] Stained-glass window sleuthing

[Scott Knitter]

My dear husband sought my help to decipher something in the stained glass
window linked below, and I'm not finding an answer. Anyone know?

It's the prophet Joel, in a window in St. Vitus Cathedral, Prague. We need
to know what his scroll means.

We can see "FONS DA <something> 3.12"

Must be a phrase from Joel 3:12, right? Doesn't seem to fit. Fons is font,
fount, fountain, source, or well; Da is the verb "to give." Joel 3:18 has
something (in a Latin version) about "fons domo Domini" - well or font of
the house of the Lord? And whence "3.12"?

Here's the image...hope it rings a bell with someone?

https://www.dreamstime.com/stock-photo-stained-glass-joel-window-st-vitus-cathedral-prague-depicting-prophet-ancient-israel-author-book-image70365153

-- 
Scott R. Knitter
Edgewater, Chicago, Illinois USA