Beeep! Technicality error
According to the laws of thermodynamics something conducts heat not cold. You don’t let cold in your house with the door open, you let heat out.
OK, whatever, shut-up Taj and get back to work, you Geek.
wistle/thermometer/compass combo
Picked one up at Bimart in the camping section for something like $3-6. I got it mostly for the compass. The thermometer seems to work, as in the water reads about what I already know the temp should be.
Paul S.
Hot tub thermometer. Home Depot, $2.95.
True, but
heat transfer is the analysis of energy transfer due to temperature differences - I just prefer to think of the icy fingers creeping in from outdoors, rather than warm drafts leaking out, i.e. in terms of reverse energy flow. But you are correct, of course.
Darkroom thermometer
If they’re still available in the digital age, you could also consider a photographic darkroom thermometer - they’re meant to be used in all sorts of nasty chemistry, so they’ll take the waters with ease.