An glossary/air-chamber/" class="glossaryLink" data-cmtooltip="0603731eba291e35b09056ade950107a" target="_blank" >air chamber without bottom, used in excavationthrough water ormud, and carrying down on its own top the beginning of a masonryfoundation. 2. Arecessed-panel/" class="glossaryLink" data-cmtooltip="337a51a56b403078c4e9dd8e1929842a" target="_blank" >recessed panel in a flat, vaulted or domed roof, which reduced weight and added a decorative element. Photo from Wikipedia. (Saylor, 1952)