Serravalle, and the lake of Sesto. Leonardo discusses the methods of supplying the canal with water, the cost of construction, the mode of dealing with the streams which cross it, etc. (Codex Atlanticus, f. 45-92.)

To Milan, cut off both from the great lakes and the main rivers of northern Italy, the question of inland navigation has been at all times vital. So the public gratitude to Leonardo, which credits him with the whole of these great works of canalisation, is easily understood.

“Under a burning sky"—I quote from Stendhal—“ Leonardo carried water into every corner of Milanese territory. It is to him the modern traveller owes the admirable landscapes, in which the fertility and verdure of the foreground are only equalled by the fantastic shapes of the snow-covered mountains, standing upon the distant horizon for the delight of the eye." 1

Now as early as the twelfth century, Lombardy could boast of considerable hydraulic works, some for irrigation, some, very probably, for navigation. In the following century the waters of the Adda were drawn upon at Cassano to form the Muzza; in the fourteenth, the stream taken from the Ticino was brought down to Milan, the canal to Pavia was made, and the Po was brought under proper control from Pont' Albero to the mouth of the Lambro.

The desire to connect Verbano, from which the marble used in building Milan Cathedral was drawn, with the centre of the capital, led, about the end of the fourteenth century, to the proposal to put the "Naviglio Grande" in direct communication with the great ditches by which the city was surrounded. To do this a difference. of level of about five "braccia" had to be neutralised. The level of the connecting canal was raised by suspending, at certain hours, all demands upon its water supply and by temporarily closing its outfall. As early as 1395 materials were thus transported "per navigium novum ad Logetum Sancti Stephani," that is to say, to the reservoir communicating with the city moat.

This system, however, had one drawback: it interrupted for more or less lengthy intervals the supply of water for other purposes than navigation. Two locks were therefore constructed by which

1 Histoire de la Peinture en Italie.

the variations of level could be strictly confined to a part of the stream sufficient to contain the rafts and boats to be accommodated, and reservoirs were formed to enable the level of the water to be raised and lowered at will.

All Leonardo's biographers have shown a desire to claim for him the exclusive credit of having formed the Martesana canal.1 The dates, however, are stubborn. As early as 1457, when Leonardo was but five years old, Duke Francesco Sforza ordered this canal, which starts from the Adda, to be begun. One of his engineers,

DESIGNS FOR WEAPONS.

Bertola da Novate,2 pushed on the work with such energy that the ducal government was able to proceed to the regular sale of the water brought down by the canal as early as 1465. Lodovico Il Moro also turned his attention to the Martesana. He not only proposed to increase its output of water, but also to make it navigable as far as the lake of Lecco. But as the Adda makes a

very long "détour" below Brivio, and as its stream is here too rapid, Lodovico thought it would be a good thing to make a canal above Brivio by which boats could descend, rejoining the Adda when the river again became navigable. The documents are silent as to the name of the engineer to whom this enterprise was entrusted. Neither does it appear that it was prosecuted with any great energy.

1 An exception must be made in favour of Pagave, who has reduced Leonardo's share in the construction of this canal to its due proportions. (See Vasari, Della Valle edition, vol. v., p. 63-64.)

Not Bertonino da Novara, as some have asserted.

In 1496 the engineering problems connected with it were still under discussion. Are we to credit Leonardo with the work? The fact is that, in 1496, Leonardo's name appears on the list of the duke's engineers, and he has left among his writings certain accounts of expenditure and notes of levels relating to the navigation of the Adda near Brivio. But we must add that from 1494 onwards, the name of Bartolommeo della Valle figures on the same list, and that the said Bartolommeo

was the identical engineer to whom, with Benedetto da Massalia, was entrusted, in 1516, the expenditure of Francis I.'s subsidy of 10,000 ducats in aid of these very same works. It is natural to suppose that when the undertaking was commenced by Il Moro, it was also to him that the inauguration of the work was entrusted.1

According to Beltrami, work on the Martesana may, then, be divided into two distinct periods; the first, before the arrival of Leonardo,

corresponds to the making of the canal from Trezzo to Milan, for which Bertola da Novate was the engineer; the other period, posterior to Leonardo's departure for the French court, includes the studies and other preparations of Della Valle and De Massalia for the Paderno canal. Although described by Carlo Pagnano as early as 1520, this

1 Leonardo da Vinci e il Naviglio Grande. My account of the various canals in the Milanese province attributed to Leonardo is borrowed from this work.

second enterprise was not completed until near the end of the sixteenth century, under the direction of Meda.

Beltrami's argument is close, as we must allow, and yet I feel some hesitation in admitting that Leonardo had nothing to do with the making of the Martesana. We have incontestable evidence that ten years later, between 1508 and 1510, he was directing important works on this very same water-way-works on which I shall have something to say in a future chapter.

The Codex Atlanticus contains some further schemes for canals, such as those for a canal to unite Cesena with Porto Cesenatico, and for canals which were actually made in Friuli.

As for the scheme for a canal to be constructed near Romorontino, of that I shall have to speak in a chapter devoted to the activities of our artist-engineer in France.

I have now said enough to show that Leonardo was not only an Utopian dreamer, but that he was also an engineer of the greatest ability, to whom the science of hydraulics especially is indebted for much of the splendid progress it has made.

The making of canals has its natural pendant in undertakings for the raising and reclamation of the marshlands they traverse. Leonardo was not the inventor of the usual process employed for this purpose, for it had been practised in Tuscany as early as the twelfth century, but he was the first to give exact instructions for it.

Did Leonardo ever think of publishing the results of such arduous and fruitful investigations? The mystery with which, as engineer and theoretical mechanician, he so carefully surrounded himself, and the precautions he took against any undue filching from his manuscripts, prove at least that even if he kept publication in view as a final end, he was in no hurry meanwhile to give his discoveries to the world through the Press. Unlike his brother Florentine, Leone Battista Alberti, who took pride in writing for humanity at large, he wrote for himself. In a collection of scientific notes at Holkham is to be found a most suggestive declaration (made in connection with a sort of diving-dress) : "In view of the wickedness of men, I do not publish or divulge the method I have invented for remaining under water, for they (men)

1 "Non nobis sed humanitati scribimus."

would make use of it in order to commit murder at the bottom of the sea, by destroying vessels and causing them to sink, together with those on board." 1

Although he would have nothing to do with esoteric principles, the head of the Milanese Academy had no idea of stripping himself for the benefit of the first comer. We cannot doubt that his curious system of writing, adopted as early as 1473, was intended to protect the invàluable discoveries set down in his note-books against the common herd. He took no less care to prevent unauthorised intrusions into his laboratory. This we know from a letter in which he speaks of one Giovanni, a German, and maker of mirrors, who worked near him in the Vatican; he declares that the said Giovanni continually strolls into his atelier, spying upon him in order to criticise him. A suspicion of this sort was a pardonable weakness in the days when Leonardo lived. No journals then existed in which discoveries could be announced and their paternity proclaimed, no patents and patent offices in which the inventor could be secured against the plagiarist.

66

Self-centred as he was, Leonardo (to quote Madame Raffalovitch) was a sower of ideas, but a sower who was not to see the harvest. His writings are like those grains of wheat which, though lying for ages inert in tombs, germinate as soon as they are restored to the conditions required for development. They only came out into the light long after his death. He stored up the fruit of his hard work and study without making any effort to bring them to the knowledge of his contemporaries. Did he think of posterity at all? Did he count upon an appendix, as it were, to an existence so full that it had something of immortality about it? How invaluable for us his manuscripts would have been had he revised, arranged, and annotated them himself! He

1 The works of Leonardo were better known than he thought, as we may gather from the following quotation from Cardan's De Subtilitate (p. 317, edition of 1550). After proclaiming that a painter is at once a philosopher, an architect, and a "dissectionis. artifex," Cardan goes on to say: "Argumento est præclara illa totius humani corporis imitatio, quam jam pluribus ante annis inchoatam a Leonardo Vincio Florentino, et pene absolutam (scimus ?), sed deerat operi tantas artifex ac rerum naturæ indagator, quantus est Vessalius." Biondo, whose Eulogy of Painting appeared in 1549, also mentions Leonardo's treatise on anatomy. We know, moreover, that Cellini acquired the treatise on sculpture, painting, and architecture, and that Serlio borrowed it from him and made use of it in his own book on perspective.