sting (together with the notes corresponding to sheet 120 r. -d of the Atlantico Codex) as regards hints at sources In the notes “acque del clonjca”, “acque del tanaglino”, Leonardo was probably referring to collections or hand-written reference books of hydraulic procedures, compiled or owned by those learned in this art. The “clojca” is probably, as Richter suggested (op. cit., II, § 1454), Simone del Pollaiuolo, known as “il Cronaca” (who died in 1508), who must have found himself repeatedly in contact with Leonardo on account of the consultations for the rooms of the Grand Council, of which “il Cronaca” was the architect (cf. Vasari, Lives, ed. cit., IV, (Florence, Sansoni, 1879), pg. 448-450), for his opinion on the static conditions of the church of S. Francesco a Monte (see above pages, pg. 13-14 and cf. Uzielli, ibid. cit.), of which Pollaiuolo was the architect (cf. Vasari, Lives, ed. cit. vol. cit., pg. 448) and finally regarding the discussion of the destination of Michelangelo’s David(cf. Gaye, Carteggio inedito d’artisti, etc., Il, Florence, Molini, 1840, pg. 456, 462; Vasari, Lives ed. cit., VII, Florence, Sansoni, 1881, pg. 155, no. 1). There is no doubt that the term “Le acque” was used to mean hydraulics. For the search made by Leonardo for useful information from those practised in this art, and the compilations he possessed, see also sheet 225 r. -b of the Atlantic Codex (Sforza period). A source which however particularly interested Leonardo from a theoretical point of view, while he was working on the treatise on water, is indicated in the notes: “la Metaura”, “Metaura d’Aristotile”[the Metaura, Aristotle’s Metaura]; while Leonardo’s annotation: “mappamondo de’ Benci” [Benci’s map of the world] is connected to his cosmographic studies (as is perhaps the other: “Giovanni Benci e ’1 libro mio e diaspri”[Giovanni Benci and My Book and Jaspers] ), to which the following from sheet 120 r.-d of the Atlantic Codex : “Il mio mappamondo che à Giovanni Benci” [my map of the world which Giovanni Benci has ] and “mappamondo di Giovanni Benci” [Giovanni Benci’s map of the world] (see also infra, pg. 22 and 23) are to be linked. which were to prove useful in the studies for the Treatise on water and the discussion of the meteorological and cosmographic questions contained in it. Such notes are believed to date back to the period slightly after Leonardo’s return to Florence – March or April 1500 –, Cf. Solmi, Leonardo, Florence, Barbera, 1900, pg. 125; Morandi, Lorenzo il Magnifico, Leonardo da Vinci e la prima grammatica italiana, etc., Città di Castello, Lapi, 1908, pg. 9-10, 12. without however entirely excluding the possibility Cf. Morandi, op. cit., pg. 11-12. that they may have been written, as suggested by some coincidences, In the document dated 25 January 1503 [1504], published by Gaye (op. and vol. cit., pg. 455-463), regarding the convocation and works of the Commission gathered to issue an opinion on the best place to put Michelangelo’s David, many names are to be found written by Leonardo among the annotations to sheet 191 r. of the Arundel Codex, and that is, those of the carpenter Francesco Monciatto, of the goldsmith Michelagnolo di Viviano, of Piero di Cosimo, of Andrea dal Monte a San Savino (whose absence is noted), of Simone del Pollajuolo, known as “il Cronaca” (see no. 12 on pg. 16), of Filippo di Filippo and Lorenzo Dalla Golpaja, the last two probably being the “Filippo and Lorenzo” nominated in the sheet mentioned of the Arundel Codex. For the names of Sansavino, of Michelagnolo the goldsmith and Monciatto cf. also the cited sheet 120 r.-d of the Atlantic Codex. The supposition comes naturally that Leonardo may have written these names and formed or reformed these connections at the time when that Commission convened, that is around or after the 25 January 1504, if the note in which Sen. Morandi (1.c.) decides that the date of 1503 should not be passed, may be taken as significant. after Leonardo, having left Valentino, had once again set up house in Florence. Certainly Leonardo, stimulated by the memory of the magnificent progress of the Lombard canalisation works and by the desire to apply such progress to Tuscany did not interrupt or quickly resumed after his return home, his elaboration of the Treatise on water, the traces of which are already drawn up in earlier or contemporary manuscripts. Cf., for example ms. A, on sheet 55 v., and following; and ms. I, sheets 73 r., 72 r., 71 v., and see infra no. 1 on pg. 22. However the compilation of the Leicester manuscript may not be dated before his return from the expedition to Romagna. Some memories contained in it which seem personal lead one to deduce a familiarity with those regions which it is not clear on what earlier occasion Leonardo could have acquired: “Li suoli, o ver falde delle pietre, non passano troppo sotto le radici de’ monti, ch’elle (son a) sono di terra (piena da) da far vasi, piena di nichi; e ancora (va) queste vanno poco sotto, che si trova la terra comune, come si vede ne’ fiumi, che scorran la Marca e la Romagnia, usciti delli Monti Appennini, e...» Sheet 36 r. (The subsoil and rocky strata do not run too deeply under the slopes of the mountain and are composed of terra cotta clay and shells. This stratum is only slightly below the normal soil, as can be seen in the rivers flowing in the Marche and in Romagna once outside the Apennine mountains) “Gran somma di nichi si vede, dove li fiumi versano in mare, perché in tali siti l’acque non sono tante salse, per la mistion dell’acque dolci, che con quelle s’uniscano; e ’l segnio di ciò si vede dove per antico li monti Appennini versavano li lor fiumi nel mare Adriano, li quali in gran parte mostrano in fra li monti gran somma di nichi insieme coll’azzurrigno terren di mare; e tutti li sassi, che di tal loco si cafano, son pieni di nichi”. Sheet 9 r. One ought to remember that Leonardo, as Cesare Borgia’s engineer, had had to deal with important excavation works (with detailed calculations and estimation of the labourers required, the costs and the savings which could be made by introducing his suggested procedures), of which there are repeated and significant traces in the Atlantic Codex, especially on sheets 368 and 370, with mention made of the works seen carried out at Pesaro (it appearing that on sheet 370 v.-c, one should read “a pesero” or “a pesere”, and thus “in Pesaro”, rather than “a pesare”, and therefore “A pesare”, as in the printed transcription of the Atlantic Codex) or to be performed in Romagna using local labour (of the “[om]ini di Rimini” [men of Rimini] mention is made on sheet 368 v.-d). Cf. also the manuscript L, sheets 24 r., 29 r. and v., 91 r., recto of the cover sheet; and Beltrami, Leonardo da Vinci e il porto di Cesenatico. (Milan, Allegretti, 1902). (A large number of