Notions on the settlement of vaulted roofs. Principal forms of vaults, en berceau, &c., &c.
Distribution of the pressures, &c.
Division of the intrados. Nature of the surfaces at the joints, &c., &c.
Lessons 13–15. Berceaux and descentes.
Lessons 16–22. Skew Arches.
Study of the general problem of skew arches.
First solution. Straight arches en échelon.
Second solution: Orthogonal appareil. True and principal properties of the orthogonal trajectories of the parallel s of an elliptical or circular cylinder. Right conoid, having for directrices the axis of the circular cylinder and an orthogonal trajectory. The inter of this conoid by a cylinder about the same axis is an orthogonal trajectory for a series of parallel s.
Third solution: helicoidal. Determination of the angular elevation at which the surfaces of the beds become normal to the head planes; construction in the orthogonal and helicoidal appareil of the curves of junction upon the heads, and the angles which they form with the curves of intrados. Cutting of the stones in these different constructions. Broken helicoidal appareil, for very long skew arches.
Helicoidal trompes at the angles of straight arches; voussures or widenings, which it is necessary to substitute near the heads at the intrados of an arch with a considerable skew; case where the skew is not the same for the two heads. Orthogonal trajectories of the converging s of a cylinder.