On school desk ink wells what does the number mean? Example... number 60, 59, and 9?

Question

On school desk ink wells what does the number mean? Example... number 60, 59, and 9? Does it tell the size of the hole the ink well goes into? I have a school desk with a hole that is about 1 7/8 dia. What size ink well fits in that hole? Thank you.

Answer 1

I'm not sure, but here is an interesting site:

Answer 2

Sounds like an antique.
It's the number desk and the row it was in.