Revolving crane for the lantern

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Working model after Leonardo da Vinci, Codex Atlanticus (BAM), fol. 808v

The dome lantern was built after Brunelleschi's death (1446), but using machines designed by him. The main device was a crane, of which two slightly different versions were employed. The first (reproduced here) was placed at the center of the dome's oculus, with its circular base inside the octagonal perimeter on which the lantern walls rested. The crane featured a fully-revolving arm with a screw system that allowed radial and vertical displacement of the load. The crane's supporting platform was raised by means of screws. The crane accurately positioned the marble blocks that formed the lower part of the lantern.

The second version of the crane featured - in addition to the revolving arm - a hoist and pulley-block for raising and positioning loads even inside the base platform. This variant model was used to construct the upper part of the lantern and to place the copper sphere and the iron cross on top of the structure.

The crane's rotation was made possible by four bell-shaped bearings.

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