Notebooks (11 page)
Authors: Leonardo da Vinci,Irma Anne Richter,Thereza Wells
Tags: #History, #Fiction, #General, #European, #Art, #Renaissance, #Leonardo;, #Leonardo, #da Vinci;, #1452-1519, #Individual artists, #Art Monographs, #Drawing By Individual Artists, #Notebooks; sketchbooks; etc, #Individual Artist, #History - Renaissance, #Renaissance art, #Individual Painters - Renaissance, #Drawing & drawings, #Drawing, #Techniques - Drawing, #Individual Artists - General, #Individual artists; art monographs, #Art & Art Instruction, #Techniques
And if you should say that the Deluge then rose with its waters above the mountains, the movement of the sea in its journey against the course of the rivers must have been so slow that it could not have carried, floating upon it, things heavier than itself; and even if it had supported them, then as it receded it would have left them strewn about in various places. How are we to account for the corals which are found every day towards Monferrato in Lombardy with wormholes in them, sticking to the rocks which have been left bare by the currents of rivers? These rocks are all covered with stocks and families of oysters, which as we know do not move, but always remain fixed by one of their valves to the rocks, and the other they open to feed upon the animalcules that swim in the water and which, hoping to find good pasture, become the food of these shells.
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Here a doubt arises, and that is: whether the Flood which came at the time of Noah was universal or not. And it would seem not, for the reasons which will now be given: We have it in the Bible that the said Flood consisted in forty days and forty nights of continuous and universal rain, and that this rain rose ten cubits above the highest mountain in the world. But if it had been the case that the rain was universal it would have formed a covering around the globe spherical in shape. And this spherical surface is in every part equidistant from the centre of its sphere; and the waters of the sphere finding themselves in the aforesaid condition it is impossible for the water upon the surface to move; because water does not move of its own accord unless to descend. How then did the water of so great a flood depart, if it is proved that it had no power of motion? and if it departed, how did it move unless it went upwards? Here, then, natural reasons fail us; and therefore to resolve such a doubt we must needs either call in a miracle to aid us, or else say that all this water was evaporated by the heat of the sun.
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) Rivers and Strata
Of the different rates of speed of currents from the surface of the water to the bottom.
Of the different cross slants between the surface and the bottom.
Of the different currents on the surface of the waters.
Of the different currents on the bed of the rivers.
Of the different depths of the rivers.
Of the different shapes of the hills covered by the waters.
Of the different shapes of the hills uncovered by the waters.
Where the water is swift at the bottom and not above.
Where the water is slow at the bottom and swift above.
Where it is slow below and above and swift in the middle.
Where it is slow in the middle and swift below, and above.
Where the water in the rivers stretches itself out and where it contracts. Where it bends and where it straightens itself.
Where it penetrates evenly in the expanses of rivers and where unevenly. Where it is low in the middle and high at the sides.
Where it is high in the middle and low at the sides.
Where the current goes straight in the middle of the stream. Where the current winds, throwing itself on different sides.
Of the different slants in the descents of the water.
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What is the current of water?
The current of water is the concourse of the reflections which rebound from the bank of the river towards its centre, in which concourse the two streams of water thrown back from the opposite banks of the river encounter each other; and these waters as they encounter each other produce the biggest waves of the river, and as these fall back into the water they penetrate it and strike against the bottom as though they were a substance heavier than the rest of the water, and rub against the bottom, ploughing it up and consuming it, and carrying off and transporting with them the material they have dislodged. And therefore the greatest depth of the water of a river is always below the greatest current.
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I perceive that the surface of the earth was from of old entirely filled up and covered over in its plains by the salt waters, and that the mountains, the bones of the earth, with their wide bases, penetrated and towered up amid the air, covered over and clad with much high-lying soil. Subsequently the incessant rains have caused the rivers to increase and by repeated washing have stripped bare part of the lofty summits of these mountains, so that the rock finds itself exposed to the air, and the earth has departed from these places. And the earth from off the slopes and the lofty summits of the mountains has already descended to their bases, and has raised the beds of the seas which encircle these bases, and caused the plain to be uncovered, and in some parts has driven away the seas from there over a great distance.
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In every concavity at the summit of the mountains we shall always find the divisions of the strata in the rocks.
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How the valleys were formerly in great part covered by lakes, because their soil always forms banks of rivers, and by seas, which afterwards through the persistent action of the rivers . . . cut through the mountains; and the rivers in their wandering courses carried away the high plains enclosed by the mountains; and the cuttings of the mountains are shown by the strata in the rocks which correspond to the sections made by the said courses of the rivers.
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A river that flows from the mountains deposits a great quantity of large stones in its bed, and these stones still retain some part of their angles and sides; and as it proceeds on its course it carries down with it lesser stones with the angles more worn away, and so the large stones make smaller ones; and further on it deposits first coarse and then fine gravel, and after this follows sand at first coarse and then more fine; and thus continuing the water turbid with sand and shingle reaches the sea.
And the sand is deposited on the seashores by the backwash of the salt waves, until the sand becomes so fine as to seem almost like water. And it will not remain on the seashores but returns with the wave by reason of its lightness, being formed of rotten leaves and other very light things. And consequently being, as has been said, almost of the nature of water, it afterwards, when the weather is calm, drops down and settles at the bottom of the sea, where by reason of its fineness it becomes compressed and resists the waves which pass over it on account of its smoothness; and in this shells are found; and this is white earth fit for pottery.
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All the outlets of the water flowing from the mountain to the sea carry stones from the mountain with them to the sea; and by the backwash of the sea water against the mountains, these stones were thrown back towards the mountain; and as the waters moved towards the sea and returned from it the stones turned with them and as they rolled their corners struck together; and as the parts of least resistance to the blows were worn away, the stones ceased to be angular and became round in form, as may be seen on the shores of Elba. And those remained larger which were less removed from their native spot; and they became smaller the further they were carried from that place; so that in the process they were converted into small pebbles and then into sand and at last into mud. After the sea had receded from the aforesaid mountains the salt deposit left by the sea with the other moisture from the earth made a compound with this shingle and this sand, so that the shingle was converted into rock and the sand into tufa. And of this we see an example in the Adda, where it emerges from the mountains of Como, and in the Ticino, the Adige, the Oglio and Adria from the German Alps, and likewise the Arno from the Monte Albano near Monte Lupo and Capraia where the largest rocks are all formed of solidified shingle of different stones and different colours.
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The first and most essential thing is stability. As to the foundations of the component parts of temples and other public buildings, their depths should bear the same relation one to another, as do the weights which are to rest upon them. Every part of the depth of the earth in a given space is composed of layers, and each layer is composed of heavier and lighter parts; the lowest being the heaviest. And the reason for this is that these layers are formed by the sediment from the water discharged into the sea by the current of the rivers which flow into it. The heaviest part of this sediment was the part that was discharged first, and so on by degrees: And this is the action of the water when it becomes stationary, while when it first moves it is carrying away. These layers of soil are visible in the banks of rivers which in their continuous course have cut through and divided one hill from another in a deep defile, wherein the waters have receded from the shingle of the banks; and this has caused the substance to become dry and to turn into hard stone, especially such mud as was of the finest texture.
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c
) The Mediterranean
Every valley has been made by its river, and the proportion between valleys is the same as that between river and river. The greatest river in our world is the Mediterranean river, which moves from the sources of the Nile to the Western Ocean.
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The bosom of the Mediterranean, as an inland sea, received the principal waters of Africa, Asia, and Europe that flowed towards it; and its waters came up to the foot of the mountains that surrounded it and formed its banks.
And the peaks of the Apennines stood up in this sea like islands surrounded by salt water. Nor did Africa as yet, behind its Atlas mountains, reveal the earth of its great plains uncovered to the sky some 3,000 miles in extent. And Memphis stood on the shore of this sea, and above the plains of Italy where flocks of birds are flying today, fishes were wont to wander in large shoals.
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Of the consumption or evaporation of the water of the
Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea, a vast river placed between Africa, Asia, and Europe, gathers within itself about three hundred principal rivers, and in addition to that it receives the rains which fall upon it over a space of three thousand miles. It returns to the mighty ocean its own waters and those that it has received; but doubtless it returns less to the sea than what it receives; for from it descend many springs which flow through the bowels of the earth and vivify this terrestrial machine. This is so because the surface of this Mediterranean is further from the centre of the world than the surface of this ocean . . . and in addition to this the heat of the sun is continually evaporating a portion of the water of the Mediterranean, and as a consequence this sea can acquire but little increase from the aforesaid rains.
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How the flow and ebb of the tide is not uniform, for on the coast of Genoa there is none; at Venice it makes a variation of two braccia; between England and France of eighteen braccia. How the current that flows through the straits of Sicily is very powerful because through these there pass all the waters of the rivers which discharge themselves into the Adriatic.
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The Danube or Donau flows into the Black Sea, which formerly extended almost to Austria and covered all the plain where the Danube flows today. And the evidence of this is shown by the oysters and cockle shells, and scallops and bones of great fishes which are still found in many places in the high slopes of those mountains; and this sea was formed by the filling up of the spurs of the Adula range which extended to the east, and joined the spurs of the Taurus range extending to the west. And near Bithynia the waters of this Black Sea poured into the Propontis falling into the Aegean Sea, that is the Mediterranean Sea, where at the end of a long course the spurs of the Adula range were separated from those of the Taurus range; and the Black Sea sank down and laid bare the valley of the Danube with the above-named provinces, and the whole of Asia Minor beyond the Taurus range to the north, and the plain that stretches from Mount Caucasus to the Black Sea to the west, and the plain of the Don this side of the Ural Mountains, that is at their feet. So the Black Sea must have sunk about 1,000 braccia to uncover such vast plains.
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It is not denied that the Nile is always turbid as it enters the Egyptian Sea and that this turbidness is caused by the soil that this river carries away continually from the places through which it passes; which soil never returns back, nor does the sea receive it except it throws it on its shores. Behold the ocean of sand beyond Mount Atlas where it was once covered with salt water.
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