In most of these enterprises it was necessary to struggle on in spite of the miasmatic atmosphere, which hung more particularly over the littoral zone, where the fresh inland water mingles with the salt water of the Mediterranean. The blending of the two waters destroyed the fresh-water plants and animals, and the deleterious gases arising from their decomposition poisoned the atmosphere. About the middle of last century an engineer, Zendrini, proposed to construct sluices separating the fresh from the salt water. This was done, and the fevers at once disappeared. In 1768, the sluices having been allowed to fall out of repair, the miasmatic scourge immediately reappeared, and it was not until they had been repaired that the sanitary condition of the villages along the coast was improved. Twice since neglect to keep the sluices in a proper condition has been punished with the same results; but from 1821 they have been maintained in thorough order, and the sanitary condition of the country has ever since been most satisfactory. Viareggio, in the centre of this malarial district, was up to 1740 hardly more than a hamlet, avoided on account of its insalubrity, but is now a seaside town, the favourite resort of numbers of visitors. Much has been done, no doubt, in draining the land, but there is still room for many improvements. The Maremma, a track between Piombino and Orbetello, remains one of the most insalubrious regions of Europe, in spite of what has been done by sanitary engineers. The inhabitants never reach a high age, and though they descend to the plain only when it is absolutely required for cultivating their fields, they frequently carry away with them the germs of disease. In the two summers of 1840 and 1841 no less than 36,000 persons suffered from fever amongst a total population of 80,000 souls, most of whom reside in villages built on hills, and only rarely visit the pestilential plain. In order to escape the pernicious influence of the poisonous air, it is necessary to reside constantly at an elevation of 325 feet above the sea, and even that does not always suffice, for the episcopal city of Sovana is notoriously unhealthy, though built at that height. Fevers occur frequently at a distance from the swamps, and Salvagnoli Marchetti is of opinion that they are due to the nature of the soil. The malaria is said to creep up clayey hills permeated by empyreumatic substances; it likewise {247} poisons the air of districts abounding in saline springs, and still more that near deposits of alum. Southerly winds are likewise most pernicious, and fevers rise highest in the valleys which are exposed to them. Places, on the other hand, which are fully open to the sea breeze are quite free from malaria, even if swamps are near, as at Orbetello and Piombino. [Illustration: Fig. 87.—THE MALARIAL REGIONS. From the Austrian Staff Map. Scale 1 : 2,700,00.]