it, at a time when the workings of his mind, having reached a considerable degree of complexity, presumed a dense network of connections between the subject areas cultivated by him and permitted certain references to their governing principles. The Leicester manuscript does not contain, unlike the other Vinci codes, dated notes enabling one to deduce the year or years when it was compiled. Only the date of the earthquake which is said to have occurred in “eighty 9”, in other words, 1489 cf. Richter’s note to this fragment, copied by him (§ 1101, pg. 266 of voI. II of the op.cit). Baratta (Leonardo da Vinci ed i problemi della terra, Turin, Bocca, 1903, pg. 197-198 and pg. 292-294) believes that Leonardo intends to refer to an earthquake which did not happen in 1489, but in 1481; in that case however Leonardo’s indication would only strengthen the conviction (given the incorrectness of the information which Leonardo produces) that the moment in which Leonardo was writing was already a long time after such disaster. , in the sea of “Satalia” We have maintained this form because it exists, as well as the more common Attalia (cf. the Novum lexicon Geographicum del Ferrari, Venice, 1738, pg. 68). , or Attalia, near Rodi is given. But another citation, more important because personal, may be used despite not offering dates to eliminate the entire decade subsequent to the year now indicated by the range of possible suppositions regarding the period in which the Code was written. Leonardo speaks – sheet 9 verso – of fossils from the mountains of Parma and Piacenza, “de’ quali, quand’io facevo il gran cavallo di Milano, me ne fu portato un gran sacco nella mia fabbrica da certi villani” (of which, when I was making the great horse in Milan a large sack full was brought to me in my workshop by certain peasants); and the memory he has of the work which he had so long awaited hoping to entrust his glory as a sculptor to it, leads one to suppose that an interval of some duration had already passed between the moment of writing and the interruption of that colossal work . Another reason for excluding the years before 1499-1500 may be found by examining the note made by Leonardo on sheet 30 verso, “contro alli mulini di Sancto Nicolò, che non vogliano ostaculo alcuno nella lor gora”, [against the water-mills of San Nicolò, which do not mean to hinder anyone in their mill-race] if, as is probable, there is a connection between this passage and the consultancy which they were to give rise to in 1499 (Florentine style) on account of the concern over the flowing of water from Monte del Re which threatened the church of S. Salvadore, also known as S. Francesco a Monte. To better ascertain the causes of this insidious phenomenon and to prevent it in the future, according to a document divulged by Uzielli Ricerche intorno a Leonardo da Vinci, second series, Rome, Salviucci, 1884, pg. 215-216. , the opinions of various architects had been requested, among them Leonardo da Vinci, who had supplied a design for setting to rights the dangerous part of the mountain, pointing out specifically the defects of the buildings and the conditions of the down flow of the waters “Leonardo da Vinci, disse quanto a S.Salvadore et a’ rimedi di quello secondo ha dato il disegno e per quello si vede da’ mancamenti dell’edifitij, e dall’acque, che vanno tra le falde delle pietre vi sono dove si fanno i mattoni, e quivi in parte sono tagliate le falde, e quella parte dell’edificio, dove sono tagliate le falde, et il mancamento, e che rifendendo, e tagliando le falde si rimetterebbe. E tener nette le fogne”. (Uzielli, op. cit, pg. 216). [Leonardo da Vinci said, in speaking of the problem of S. Salvadore and the remedies to adopt according to his design, that the subsidence of the buildings was provoked by water seeping between the layers of stone underground into the clay. Here these layers are in part cut and between the part of the buildings where the strata are cut and the subsidence, if the strata were cut again the drains would be kept free]. The strata or layers which Leonardo was referring to slope in fact towards Porta S. Nicolò (Uzielli, op. cit., pg. 213, quoting Grattarola (G.), Momo (F.) and Alessandri (A.), section of the viale dei Colli in Florence, in Bull. del Com. geologico. Year 1870, pg. 124-125). . It is probable that the water mills of S. Nicolò did not just use water from the Arno but also the water which came down from Monte del Re or Monte S. Salvadore, above the place where they were situated We owe to the kindness of Prof. Tommaso Gotti some indications on the site of those mills which, if we are speaking of the group closest to the Porta S. Nicolò, belonged from the XIII century onwards to the monks of S. Miniato al Monte; they have confirmed such theory. ; that the millers, fearing that their immediate interests would be affected negatively, had protested in advance against any alteration to the way things were; and that the specious motive of their protest had given Leonardo an opportunity to reproach them and observe, with particular attention to their case, that “l’acqua, che