(1) The "depth of air cell" (air space between shell membranes, normally in the large end of the egg) is the distance from its top to its bottom when the egg is held air cell upward.

(2) A "practically regular" (AA or A quality) air cell is an air cell that maintains a practically fixed position in the egg and shows a fairly even outline with not more than 2/8 inch movement in any direction as the egg is rotated.

(3) A "free air cell" (B or C quality) is an air cell that moves freely toward the uppermost point in the egg as the egg is rotated slowly.

(4) A "bubbly air cell" (B or C quality) air cell is a ruptured air cell resulting in one or more small separate air bubbles usually floating beneath the main air cell.