The inverted arch is better for giving a shoulder than the ordinary one, because the former finds below it a wall resisting its weakness, whilst the latter finds in its weak part nothing but air.
Three slight sketches of sections on the same leaf—above those reproduced here—are more closely connected with the large drawing in the centre of
Pl. C, No. 4 (M.S, Tr. 41) which shows a section of a very elevated dome, with double vaults, connected by ribs and buttresses ingeniously disposed, so as to bring the weight of the lantern to bear on the base of the dome.
A sketch underneath it shows a round pillar on which is indicated which part of its summit is to bear the weight: “il pilastro sara charicho in . a . b.” (The column will bear the weight at a b.) Another note is above on the right side: Larcho regiera tanto sotto asse chome di sopra se (The arch supports as much below it [i. e. a hanging weight] as above it).
Pl. C, No. 1 (C. A. 303a). Larger sketch of half section of the Dome, with a very complicated system of arches, and a double vault. Each stone is shaped so as to be knit or dovetailed to its neighbours. Thus the inside of the Dome cannot be seen from below.
MS. C. A. 303b. A repetition of the preceding sketch with very slight modifications.
[Figs. 1. and Fig. 2. two sketeches of the dome]
MS. Tr. 9 (see Fig. 1 and 2). Section of the Dome with reverted buttresses between the windows, above which iron anchors or chains seem to be intended. Below is the sketch of the outside.
PI. XCIX, No. 3 (C. A., 262a) four sketches of the exterior of the Dome.
C. A. 12. Section, showing the points of rupture of a gothic vault, in evident connection with the sketches described above.
It deserves to be noticed how easily and apparently without effort, Leonardo manages to combine gothic details and structure with the more modern shape of the Dome.
The following notes are on the same leaf, oni cosa poderosa, and oni cosa poderosa desidera de(scendere); farther below, several multiplications most likely intended to calculate the weight of some parts of the Dome, thus 16 x 47 = 720; 720 x 800 = 176000, next to which is written: peso del pilastro di 9 teste (weight of the pillar 9 diameters high).
Below: 176000 x 8 = 1408000; and below:
Semjlio e se ce 80 (?) il peso del tiburio (six millions six hundred (?) 80 the weight of the Dome).
Bossi hazarded the theory that Leonardo might have been the architect who built the church of Sta. Maria delle Grazie, but there is no evidence to support this, either in documents or in the materials supplied by Leonardos manuscripts and drawings. The sketch given at the side shows the arrangement of the second and third socle on the apses of the choir of that church; and it is remarkable that those sketches, in MS. S. K. M. II2, 2a and Ib, occur with the passage given in Volume I as No. 665 and 666 referring to the composition of the Last Supper in the Refectory of that church.
F. The Project for lifting up the Battistero of Florence and setting it on a basement.
Among the very few details Vasari gives as to the architectural studies of Leonardo, we read: “And among these models and designs there was one by way of which he showed several times to many ingenious citizens who then governed Florence, his readiness to lift up without ruining it, the church of San Giovanni in Florence (the Battistero, opposite the Duomo) in order to place under it the missing basement with steps; he supported his assertions with reasons so persuasive, that while he spoke the undertaking seemed feasable, although every one of his hearers, when he had departed, could see by himself the impossibility of so vast an undertaking.”
[Footnote: This latter statement of Vasari’s must be considered to be exaggerated. I may refer here to some data given by LIBRI, Histoire des sciences mathematiques en Italie (II, 216, 217): “On a cru dans ces derniers temps faire un miracle en mecanique en effectuant ce transport, et cependant des l’annee 1455, Gaspard Nadi et Aristote de Fioravantio avaient transporte, a une distance considerable, la tour de la Magione de Bologne, avec ses fondements, qui avait presque quatre-vingts pieds de haut. Le continuateur de la chronique de Pugliola dit que le trajet fut de 35 pieds et que durant le transport auquel le chroniqueur affirme avoir assiste, il arriva un accident grave qui fit pencher de trois pieds la tour pendant qu’elle etait suspendue, mais que cet accident fut promptement repare (Muratori, Scriptores rer. ital. Tom. XVIII, col. 717, 718). Alidosi a rapporte une note ou Nadi rend compte de ce transport avec une rare simplicite. D’apres cette note, on voit que les operations de ce genre n’etaient pas nouvelles. Celle-ci ne couta que 150 livres (monnaie d’alors) y compris le cadeau que le Legat fit aux deux mecaniciens. Dans la meme annee, Aristote redressa le clocher de Cento, qui penchait de plus de cinq pieds (Alidosi, instruttione p. 188— Muratori, Scriptores rer. ital., tom. XXIII, col. 888.—Bossii, chronica Mediol., 1492, in-fol. ad ann. 1455). On ne concoit pas comment les historiens des beaux-arts ont pu negliger de tels hommes.” J. P. R.]
In the MS. C. A. fol. 293, there are two sketches which possibly might have a bearing on this bold enterprise. We find there a plan of a circular or polygonal edifice surrounded by semicircular arches in an oblique position. These may be taken for the foundation of the steps and of the new platform. In the perspective elevation the same edifice, forming a polygon, is shown as lifted up and resting on a circle of inverted arches which rest on an other circle of arches in the ordinary position, but so placed that the inverted arches above rest on the spandrels of the lower range.
What seems to confirm the supposition that the lifting up of a building is here in question, is the indication of engines for winding up, such as jacks, and a rack and wheel. As the lifting apparatus represented on this sheet does not seem particularly applicable to an undertaking of such magnitude, we may consider it to be a first sketch or scheme for the engines to be used.
G. Description of an unknown Temple.
Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.