The lagoons of Venice are a large basin, covering an area of one hundred and eighty-four square miles, and composed of shoal banks, intersected in all directions by deep channels. The form of the lagoons, roughly speaking, is that of a bent bow, a segment of a circle and the line that cuts it. The curved line follows the shore of the mainland; the straight line is composed of a number of long narrow islands, or lidi, which close the lagoons on the sea side, and shut out the Adriatic. It is these lidi, these sandy islands which are the important fact in the structure of the lagoons; without them the lagoons would not exist, and their surface would simply be added to the sea, which, in that case, would find its real shore not, as at present, on the outer side of these islands, but upon the mainland itself.
The lagoons are the result of overflowing by the sea and by the rivers which used to discharge their waters into them. But partly to avoid the danger from spring and autumn floods, partly on account of the malaria produced by the mingling of salt water and fresh, the Sile and Piave were connected at their mouths, and now empty themselves directly into the sea. The Brenta alone sends very considerable volume of fresh water into the lagoon. It is from the Adriatic that these waters come which twice a day flood all the shallows of this basin, and sweep through the canals of Venice, cleansing the water streets, and performing the task of ” pure ablution,” round her ancient walls.
The lidi are not only intimately connected with the origin and general structure of the lagoons, but they are now the bulwark of Venice against the sea. That narrow strip of sandy dune, never more than half a mile in width, alone stands between Venice and the Adriatic, which would other-wise break in upon the lagoons and sweep the city down. When the sirocco is thundering on the sands of the Lido, and its boom is borne high in the air, one cannot help picturing the ruin that would follow should the slender barrier of sand give way beneath the battery of the stormy sea. Once or twice the sea has broken through this frail defence, and threatened the city; and almost the last important work undertaken by the Republic was the fortification of the lidi, at their weakest points by the Murazzi, great sea-walls, some formed by rough blocks of Istrian stone piled anyhow along the shore, others built up of solid and cemented masonry.
The lagoon of Venice is not a semi-stagnant marsh, but a water basin where the activity of the currents and tides is unceasing. Nor is the lagoon, in spite of its apparent unity, to be considered as one large tidal lake. It is, in fact, a complex of four water systems, quite distinct from one another, each with its main channels and tributary streams.
It is the lidi that determine this peculiar internal structure of the lagoon basin, which distinguishes it from other bodies of water, and makes it neither marsh nor lake nor sea, but something different from any of these. In the line of the lidi there are four breaches or ports, which give passage to the water between the lagoon and the open sea; they are the ports of Chioggia, Malamocco, Lido, and Tre Porti. There used to be a fifth, the port of Sant’ Erasmo, but that was closed in 1474, in order to increase the volume of water at the Lido port. Only a very small body of water now passes through its mouth; and for all purposes of understanding the internal economy of the lagoons, we have to deal with the four ports above mentioned. It is through these four mouths that the sea comes flooding in upon the lagoons at the flow, and passes out at the ebb ; and it is upon these ports that the whole system of currents and tides, which vivify the lagoons, is dependent.
The surface of the lagoons is traversed by five main channels, or water highways; and all of them centre in Venice. The course of these channels is marked by groups of posts, driven into the mud at regular intervals. But besides these principal thoroughfares there is a network of smaller canals, many of them ending nowhere, lost in the shoals, undistinguished by any sign-posts and known only to fishermen, smugglers, and those who have the practice of the lagoons. The five main channels are first, that of the Lido, familiar to every one who knows Venice ; it conducts to the sea by way of San Nicoletto and Sant’ Andrea. This was the great port of the Venetian Republic. By the Lido mouth her galleys sailed to war; her argosies came laden home, and, every festival of the Ascension, the Doge in the Bucentoro passed out to wed the Adriatic. The great eastern canal leads by Murano, Burano, Mazzorbo, and Torcello to the mainland near Altino. The northern channel, between Mestre and Venice, was once the usual approach to the sea-city before the railway bridge was built. A fourth canal leads to Fusina, also on the mainland, where the Brenta, or rather part of the Brenta, flows into the lagoon. And last, and most important of all, there is the canal to Malamocco and Chioggia, by which all the large shipping reaches Venice, now that the older port of the Lido has been allowed to silt up. Any one who wishes to see the lagoons might do worse than take these five canals in turn. From each of them he would obtain a different view of Venice, a fresh idea of the singular foundations from which the city rises, a varied composition of campanili and domes against the constant background of sky and Alps.
There are few great surfaces of water which are as sensitive as the lagoons of Venice. And this sensitiveness is the cause of constant change, change which surprises even those who know the lagoons best. The picturesque charm of the lagoon resides in its two main features the water and sky; and the secret of their fascination is their endless variety secured by the vastness of the space which they include. The city itself and its attendant isles are always present, like the gems that grace the setting; but the setting changes infinitely, The islands and the stationary Alps that bound the vision, alone remain immovable; all else in the landscape of the lagoons is shifting continually.
In the water there is the perpetual flux and reflux of the tides in endless operation; now revealing large tracts of green or brown upon the shoals, now cloaking all beneath one wide unbroken mantle of grey sea. The colour of the water surface itself is continually undergoing a prismatic change. The prevailing tone is grey, but grey of every huegrey haze suffused by the low winter sun, blue grey, grey warmed with yellow or with pink, soft and delicious, the result of sirocco grey that is hard and cold under the sun or pure and silvery white beneath the moon. Grey is the dominant tone of colour, but at sunset and sunrise, there are the more gorgeous hues of rose and crimson, of orange, of purple, and of bronze. It would be impossible to discover any place where the pageantry of colour is more certain and more varied than it is upon the lagoons.
Not only on the water surface is there manifold change, but the same is happening hourly in the water body; the one is felt in the wide sweep of vision over the lagoon level, the other in the minute section which lies below our boat. These changes of tone in the water body depend upon action of wind, tide, and weather. If the sirocco has stirred the sands on the Lido, then the incoming tide will be opaquely green and mottled here and there with yellow stains such as are sometimes seen in jade; or if the sea be calm, the flowing tide will sweep through the canals clear and pale as aqua-marine, or clear and dark as the rare stone, the tourmaline.
The prevailing tone upon the water surface is grey, the prevailing tone in the water body is green. And if that green be transparent, the forestry of water weeds which clothe the bed of the lagoon, with all its finny denizens, the wavering of the seaweed tips beneath the current, the variety of colour upon the long streamers, make the few square feet below the boat as beautiful to contemplate as all the miles of water surface that stretch away on every side.
But the sky, even more than the water, is the glory of the Venetian lagoon. Nowhere, except at sea, could the eye master so vast an arc. And thus there is laid open to the contemplation nature busied in various occupations, for what is going on in the far east stands apart from that which engages wind and sunshine in the west; and sea and mountains, to the south and north, have different tasks allotted them. The heavens display the manifold workmanship of nature in unceasing activity. The clouds, moulded at their borders by the opposing atmosphere, mass their domes and pinnacles and mountainous buttresses under the compulsion of some internal force desiring to expand, until their edges are frayed and torn, and the storm-clouds burst and sweep across the sky. The premonition of the coming wind is given by the lifted clouds upon the far horizon, the long straight line below, the billowing vanguard above, as the whole cloud-wall is buoyed and driven before the gale. There are quiet skies, with fields of pearly grey and cirrus flecked above the tranquil misty veils that part and leave interspaces of pure blue. There are the thunder-clouds that hang upon the hills and cool and melt away as night wears on. Above all there is the splendour of Venetian sunsets, and more especially the stormy ones, outflaming any painters canvas. The ominous masses of dun cloud, blown from the eastward ; the rainbow that rises and spans the city, high and brilliant against sombre clouds urged so violently forward by the wind that their foremost battalions curve like the arc of a bow, and are kindled to tawny purple by the setting sun. Then the bursting of the storm; the riving of the cloud strata revealing behind them steel blue layers, and further still behind, a hand’s breadth of serene blue sky. And all the while the sun is going down, to westward in heavens that are calm and suffused with limpid golden light, unheeding of the tempest that sweeps towards the hills.
These operations of nature are so immense and so aloof, that personal human emotion seems to fall away before them, retiring to the vanishing point, and the spirit is left naked and alone, facing the radical forces of the universe.