Ballpark the temperature. Place the dutch oven in the coals and then hold your hand over it at the level of the sides. Count backwards by 50 starting at 550 (550, 500, 450) until you have to remove your hand. That will give you an approximate temperature produced by your coals.
GENIUS!!! Cooler Corn... Don't have a pot big enough to cook corn on the cob for a big group of people at your summer party or while camping? Don't have or wanna mess with a grill? Clean out a cooler, put husked corn in, add boiling water to cover. Corn will be perfect in 30 mins and stay for 3 hrs!