The drum (tamburo) of these cupolas is generally octagonal, as in the cathedral of Florence, and with similar round windows in its sides.  In Pl.  LXXXVII No. 2 it is circular like the model actually carried out by Michael Angelo at St. Peter’s.

The cupola itself is either hidden under a pyramidal roof, as in the Baptistery of Florence, San Lorenzo of Milan and most of the Lombard churches (Pl.  XCI No. 1 and Pl.  XCII No. 1); but it more generally suggests the curve of Sta Maria del Fiore (Pl.  LXXXVIII No. 5; Pl.  XC No. 2; Pl.  LXXXIX, M; Pl XC No. 4, Pl.  XCVI No. 2).  In other cases (Pl.  LXXX No. 4; Pl.  LXXXIX; Pl.  XC No. 2) it shows the sides of the octagon crowned by semicircular pediments, as in Brunellesco’s lantern of the Cathedral and in the model for the Cathedral of Pavia.

Finally, in some sketches the cupola is either semicircular, or as in Pl.  LXXXVII No. 2, shows the beautiful line, adopted sixty years later by Michael Angelo for the existing dome of St. Peter’s.

It is worth noticing that for all these domes Leonardo is not satisfied to decorate the exterior merely with ascending ribs or mouldings, but employs also a system of horizontal parallels to complete the architectural system.  Not the least interesting are the designs for the tiburio (cupola) of the Milan Cathedral.  They show some of the forms, just mentioned, adapted to the peculiar gothic style of that monument.

The few examples of interiors of churches recall the style employed in Lombardy by Bramante, for instance in S. Maria di Canepanuova at Pavia, or by Dolcebuono in the Monastero Maggiore at Milan (see Pl.  CI No. 1 [C.  A. 181b; 546b]; Pl.  LXXXIV No. 10).

The few indications concerning palaces seem to prove that Leonardo followed Alberti’s example of decorating the walls with pilasters and a flat rustica, either in stone or by graffitti (Pl.  CII No. 1 and Pl.  LXXXV No. 14).

By pointing out the analogies between Leonardo’s architecture and that of other masters we in no way pretend to depreciate his individual and original inventive power.  These are at all events beyond dispute.  The project for the Mausoleum (Pl.  XCVIII) would alone suffice to rank him among the greatest architects who ever lived.  The peculiar shape of the tower (Pl.  LXXX), of the churches for preaching (Pl.  XCVII No. 1 and pages 56 and 57, Fig. 1-4), his curious plan for a city with high and low level streets (Pl.  LXXVII and LXXVIII No. 2 and No. 3), his Loggia with fountains (Pl.  LXXXII No. 4) reveal an originality, a power and facility of invention for almost any given problem, which are quite wonderful.

In addition to all these qualities he propably stood alone in his day in one department of architectural study,—­his investigations, namely, as to the resistance of vaults, foundations, walls and arches.

As an application of these studies the plan of a semicircular vault (Pl.  CIII No. 2) may be mentioned here, disposed so as to produce no thrust on the columns on which it rests: volta i botte e non ispignie ifori le colone. Above the geometrical patterns on the same sheet, close to a circle inscribed in a square is the note: la ragio d’una volta cioe il terzo del diamitro della sua ... del tedesco in domo.