Instead of placing the dough pieces for baking on the bottom or sole of the baking chamber, the Jews put the pieces on the sides.
Being damp and sticky they remained in place intil they had dried out, when they fell to the bottom of the oven.
The fact ovens based on this simple design formed the majority of those in use throughout Europe until little more than two centuries ago.
Although some of the early Roman ovens had chimnesy to improve the draught and carry away steam, it was many centuries before chimneys were commonly used or dampers incorporated so that the heat could be more effectively controlled." ---The Story of Bread, Ronald Sheppard & Edward Newton [Charles T. 107-109) ""When I break your staff ten women shall bake your bread in one oven, and shall deliver your bread again by weight; and you shall eat, and not be satsified." ---Lev. This type of oven may have been a small earthenware cylindar called tannur in the Bible as it is by present-day rural north Africans who still use it.
Kiple and Kriemhild Conee Ornelas, Volume 1 [Cambridge University Press: Cambridge] 2000 (p.