On Malaria. 323 



efficacy; and for this purpose I beg leave to quote the instance of 

 reclaiming the Val de Chiana, to shew ihsit physical causes may be con- 

 trolled, by the skillful application of human industry. 



Near the city of Crotona was a lake, of no very great dimensions, 

 but surrounded with marshes which diffused the most pestilential ex- 

 halations. The Tuscan genius and spirit, at that time in its zenith, 

 suggested and executed a plan for draining the lake and its marshes. 

 A canal leading to the Arno carried off the water, and three thousand 

 acres were brought into cultivation. It was not thrown into a vast 

 domain, and consigned to some individual proprietor, in whose hands 

 the neglected parts would soon have run down the remainder, but 

 was divided into seventy farms, which were separated by roads, and 

 bordered with canals. On each farm a rural dwelling was erected ; 

 every inch of ground was cultivated ; the crops, consisting of corn, 

 wine, vegetables and silks were gathered in season, and not a foot of 

 land was left to run waste. "The plain of Crotona in 1813 dis- 

 played one of the noblest triumphs of human industry ;"* fertile 

 fields where had been a pestilential morass, a salubrious atmosphere, 

 and an industrious and happy population. Volney states that he " wit- 

 nessed the drying up of a small pool and rivulet in Holland completely, 

 to free a family from the annual visits of intermittent fevers." I might 

 illustrate this part of the subject with many examples from foreign 

 countries, in proof of the salutary effects of draining ; particularly the 

 benefit produced to the health of the inhabitants, by reclaiming 

 large tracts of fens and bogs in the eastern counties of England, a 

 benefit felt even in the metropolis ; and a few cases nearly analogous 

 in the United States might be cited ; but I am not aware that the ex- 

 periment has been thoroughly tested in this country. 



In order to make the draining effectual, ditches should be broad and 

 deep enough to convey off the superfluous water of the rains ; and 

 cross cuts or sluices should lead from hollows to the main outlet. JVo 

 weeds should be allowed to grow on the banks, and the bottoms should 

 be scraped annually, to clear them from mud and aquatic plants. 

 It is of particular service to cut the weeds, grasses and shrubs, after 

 the coming of frost, and to burn them upon the marsh ; as the ma- 

 terials, which would be injurious in the following hot season, are thus 

 changed into a species of manure, that hastens the progress of the 



** Chateauvieux's Travels. 



