love that picture up there...
i don't trust glass thermometers... although people have been using them for years... i can't calibrate or place them where i really want them... i have fish tanks, and before i use a digital thermometer on a reptile or anything else, i compare it to my apex controller on my fish tank... if it reads the same exact temp as the controller, it's good...
the only thing that does stress me out, and i know i'm not alone... is the fact that digital thermometers will show you the tiniest fluctuation in the bator... i get upset when it fluctuates from 99.5° to 99.1° non stop... LOL... i stare at it for a couple of hours until i realize that i'm going to go crazy if i don't leave it alone...