a) (MS. B, 34b, page 44 Fig. 3). In the middle of each side a column is added, and in the axes of the intercolumnar spaces a second row of columns forms an aisle round the octagon. These are placed at the intersection of a system of semicircles, of which the sixteen columns on the sides of the octagon are the centres.
b) The preceding diagram is completed and becomes more monumental in style in the sketch next to it (MS. B, 35a, see p. 45 Fig. 1). An outer aisle is added by circles, having for radius the distance between the columns in the middle sides of the octagon.
c) (MS. B. 96b, see p. 45 Fig. 2). Octagon with an aisle round it; the angles of both are formed by columns. The outer sides are formed by 8 niches forming chapels. The exterior is likewise octagonal, with the angles corresponding to the centre of each of the interior chapels.
Pl. XCII, No. 2 (MS. B. 96b). Detail and modification of the preceding plan--half columns against piers--an arrangement by which the chapels of the aisle have the same width of opening as the inner arches between the half columns. Underneath this sketch the following note occurs:_ questo vole - avere 12 facce - co 12 tabernaculi - come - _a_ - _b_. _(This will have twelve sides with twelve tabernacles as_ a b._) In the remaining sketches of this class the octagon is not formed by columns at the angles.
The simplest type shows a niche in the middle of each side and is repeated on several sheets, viz: MS. B 3; MS. C.A. 354b (see Pl. LXXXIV, No. 11) and MS. Ash II 6b; (see Pl. LXXXV, No. 9 and the elevations No. 8; Pl. XCII, No. 3; MS. B. 4b [not reproduced here] and Pl. LXXXIV, No. 2)._
_Pl. XCII, 3 (MS. B, 56b) corresponds to a plan like the one in MS. B 35a, in which the niches would be visible outside or, as in the following sketch, with the addition of a niche in the middle of each chapel.
Pl. XC, No. 6. The niches themselves are surrounded by smaller niches (see also No. 1 on the same plate).
b) No. 2 on the same plate. Underneath there is the remark:_ "quest'e come le 8 cappele ano a essere facte" _(this is how the eight chapels are to be executed).
c) Pl. LXXXVIII, No. 5. Elevation to the plans on the same sheet, it is accompanied by the note:_ "ciasscuno de' 9 tiburi no'uole - passare l'alteza - di - 2 - quadri" _(neither of the 9 domes must exceed the height of two squares).