Models of the masonry layering and of the geometrical structure of the dome

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The model presents a cross-section of one side of the dome, including its two rims and the beginning of the adjacent sides, at the height of 30? from the springing point over the drum. It displays the herring-bone spirals that continually block the masonry work, the empty spaces between the outer and the inner shells, the inward slope of the brick beds, and the slack-line profile of the brick rows.

The metal model next to the masonry model explains the method for tracing the pointed-fifth curvature. It also shows that the characteristic slack-line profile of the brick beds between the rims is due to their lying on the surface of an inverted cone whose axis coincides with that of the dome.

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