Latin inscription in a sundial

Hello!
I was wondering if anyone could help me translating a sentence written in a very old sundial painted in the walls of my school (the school was built in 1349). When we discovered it, there were some parts missing and I hoped someone here could guess what came before. [The missing parts are (...)]

(...)ol mea contegit? Imò
(...) umbra tuos.

It was eroded with the time and now no one knows what was originally written.
Maybe if anyone knows common mottos for ancient sundials we can find out.
The sundial only marks the hours corresponding to the school's schedule.

If it helps, the missing part has almost the same lenght as the visible words.

Thanks in advance,
Emily.