Each page has a square to simulate a window. Wavy horizontal lines from bottom to top simulate a water level. The height of the lines progressively increases and decreases as the pages are flipped. The 40 pages are the same as Noah's biblical experience with the flood as depicted when the pages are flipped. -- Source of annotation: Marvin or Ruth Sackner. https://aspace.lib.uiowa.edu/repositories/5/archival_objects/892375 Accessed November 08, 2024.