The power went out yesterday, and tiny cheeps of protest were heard...so the chicks came in from the big brooder to a smaller tub in the kitchen, near the stove with the pilot light. I had four empty 1.75 liter vodka bottles (I had just made a big batch of limoncello the day before ), so we filled them up with hot water, wrapped them in towels, and laid them side by side to fill up the bottom of the brooder. The chicks snuggled in happily on their "waterbed", and were warm and happy again. The large thermal mass meant that the brooder stayed at a good temperature for about 6 hours before I had to add more hot water. Power's back this morning! Everybody made it through the night healthy and happy.