L'arco rivescio e migliore per fare spalla che l'ordinario, perche
il rovescio trova sotto se muro resistete alla sua debolezza, e
l'ordinario no trova nel suo debole se non aria

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.

[Footnote: _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._