By Ken ja Mimi from da UP (Kenjamimi) on Monday, March 15, 2010 - 09:09 pm:
The vent used to be built into one of the back wall corners, using two 5" or 6" boards to the roof and then continued up for a ways with 4 boards and a little roof at the top of it. As the vent 'worked', the fresh air would come in from the door or the cresent moon. 'Nough said?