Heirloom

Mr. W recently inherited a rather lovely old clock which once belonged to his great grandfather.  It now hangs on the wall in our guest room, and because it is quite delicate, and because I have ham-fisted cleaning ladies, I have rather rudely stuck a little note on the glass covering the clock's front which says "DO NOT TOUCH".  It occurred to me the other day, as I was putting fresh sheets on the bed that our guests must think I am quite bossy!!!!

Can any of you German speakers translate what is written here?  It says:

Die Lehrer der Volksschule Constanz ihrem verehren collegen Josef Wiehl zum 40 jahrigen en Julilaum den 13 Juli 1879