959

The ebb and flow of the tide.

That the flow and ebb are not general; for on the shore at Genoa there is none, at Venice two braccia, between England and Flanders 18 braccia. That in the straits of Sicily the current is very strong because all the waters from the rivers that flow into the Adriatic pass there.

[Footnote: A few more recent data may be given here to facilitate comparison. In the Adriatic the tide rises 2 and 1/2 feet, at Terracina 1 1/4. In the English channel between Calais and Kent it rises from 18 to 20 feet. In the straits of Messina it rises no more than 2 1/2 feet, and that only in stormy weather, but the current is all the stronger. When Leonardo accounts for this by the southward flow of all the Italian rivers along the coasts, the explanation is at least based on a correct observation; namely that a steady current flows southwards along the coast of Calabria and another northwards, along the shores of Sicily; he seems to infer, from the direction of the fust, that the tide in the Adriatic is caused by it.]

Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.

Notebooks of Leonoardo da Vinci
XVI: Physical Geography.
. . .
The theory of Plato.
939
That the flow of rivers proves the slope of the land.
940
Theory of the elevation of water within the mountains.
941
The relative height of the surface of the sea to that of the land.
942,
943,
944,
945
Refutation of Pliny’s theory as to the saltness of the sea.
946,
947
The characteristics of sea water.
948,
949
On the formation of Gulfs.
950,
951
On the encroachments of the sea on the land and vice versa.
952,
953,
954
The ebb and flow of the tide.
955,
956,
957,
958,
959,
960
Theory of the circulation of the waters.
961,
962
Observations in support of the hypothesis.
963,
964,
965,
966,
967,
968,
969
On the way in which the sources of rivers are fed.
970
The tide in estuaries.
971
confluence.
972,
973,
974
Whirlpools.
975
On the alterations in the channels of rivers.
976
The origin of the sand in rivers.
977,
978
The formation of mountains.
979
. . .