MAIISIIES are those places of greater or less extent on the earth. surface, where the soil is almost constantly soaked with water. The the bog, the fen, and the morass, are so many different names for the same thing, or modifications which have not yet been defined. Whether marshes be considered with regard to their advantages or disadvantages, they ere equally Interesting, and are objects that call for the attention of Individuals and sometimes of states. The advan tages which they offer are of limited extent, and may be divided into qimtaneous and artificial. The former consist In the natural pro ductiorui which are furnished by some of them, of which peat is unquestionably the most important. (Ireland, Holland.) (Boo, in NAT. HIST. Div.] Some furnish Iron-ore in considerable quantity— bog iron-ore—which is formed in them by the action of decomposing vegetable matter on water holding gaits of iron in solution,ariaing from the decomposition of other iron ores; and, though generally of a bad kind, owing to the phosphorus it contains, it is sometimes very good, and worked with advantage (Siberia); others supply aquatic game in abundance, which is a great resource to the neighbouring inhabitants, either for consumption or as an article of commerce (the marshes of Tuscany); others again abound in eels and other fish ; and some, as those of the Saone in France, and those of Poland, the Ukraine, and Bohemia, are valuable for the myriads of leeches which they furnish, and which are sent to distant parts. The soil itself, dug up from the marshes, which is called bog-earth, and the upper surface of the peat bogs, burnt or unburnt, are in many cases considered an excellent manure, and employed as such. (Poland, France.) The reeds, rushes, willows, &e., which grow so abundantly in certain marshy lands, are in many places objects of considerable importance. (Italy, Holland.) The artificial advantages to which marshes may be turned are confined chiefly to the cultivation of rice, where climate and other circumstances are favourable to the growth of this grain. (North America, Hungary.) The disadvantages of marshes are great : they are in general fatal to health, and agriculture suffers by the loss of all the marshy land. That health is materially injured by the pestilential air of marshes is evident from the fact that the ordinary mean length of life in their neighbourhood is very low. Cattle are also great sufferers from the influence of marshy grounds. The engineer Rauch says," Marshes are the ulcers of the earth, which blur the fair face of nature, where all should be beauty ; and from these infectious sores the languor of death extends far and wide over all that should live and flourish ;" but the details of their baleful influence are nowhere more strikingly set forth than in the prize essay ou this subject, by M. Hamel, of Paris.
A particular case, on a part of the Italian coast, derived however from another authority, will well illustrate this subject, so far as regards maritime marshes. Both ancient and modern authors have announced the fatal effects produced in the neighbourhood of marshes by the admixture of their waters with that of the sea, and a local belief of the same thing is very common and strong on the borders of the Mediterranean in Italy. On the south of the Ligurian Apennines is a marshy shore, bounded on the west for twelve miles by that sea, on the south by the river Serchio, and un the north by the Frigido, a torrent commencing at the foot of the mountains, in the state of Massa di Carrara, running three or four miles over the land, and then falling into the sea. The plain is from two to four miles wide, and is traversed by a few short streams, two of which divide it into three separate basins. The rain and spring waters which flow into these are slowly discharged into the sea by natural or artificial canals, penetrating the sand-banks on the sea-side. The level of these stagnant waters is between the levels of high and low tide in the sea, there being but little difference between these two points in this part of the Mediter ranean. In this state of things, when the waters of the sea arose front any circumstance (unless the waters of the marshes were very high), they used to return up the ditches, fill the basins, and inundate the country to the foot of the mountains ; and with a north-west wind, the waves used to penetrate with force to the interior. The mixture of fresh and salt-water thus formed, and which in summer was rarely changed, became corrupt, and spread infection of the most destructive kind over the neighbourhood. In this way the effects of the malaria were reproduced annually ; the population, though small, presented feeble infants and diseased men, old age being unknown there. All attempts to avoid the scourge by living on the hills, or in the interior, and frequenting the plain only when the business of cultivation required, were vain; the inhabitants fell victims to the extensive influence, and much more rapidly did a stranger suffer from the deleterious atmosphere : a sojourn for ono single night, in the months of August and September, causing inevitable death to the incautious traveller.