On Malaria. 30& 



lie in a climate scarcely productive of malaria, the demonstra- 

 tion of their pernicious qualities in Italy and Switzerland is 

 ample. The causes, immediately, are various ; and I need 

 not do more than name them. Their deltas, whether at the 

 exits or entrances of the rivers, are meadows of the worst kind, 

 because subject to inundation ; their borders are often marshy; 

 and, in addition, they frequently contain creeks or shallow 

 places, productive of putrefying aquatic vegetables and stag- 

 nant water ; while, in some situations, as diminished by the 

 heat of summer, they often also expose offensive mud, gene- 

 rative of the same poison. 



With respect to rivers, I may commence by one general re- 

 mark. It is the observation of Volney, that there is not a river 

 in America that does not produce malaria ; and when, after 

 enumerating in addition, vaUies, woods, mill-ponds, meadows 

 and lakes, he says that, through his whole circuit, he did not 

 find a dozen houses without fevers ; it is a testimony which is 

 too pointed not to be quoted as to this and many other of the 

 facts and places which have here been enumerated. And in 

 France and Italy, the same opinion prevails ; while, if we con- 

 sider the reasons, it is apparent in the nature of their banks, 

 producing a marshy vegetation ; in the diminution, during 

 summer, of their waters, exposing mud ; in their casual inun- 

 dations, rendering the inclosing lands wet ; and in the general 

 character of the soil and vegetation by which they are bounded. 

 How these circumstances may exist and act in our own coun- 

 try, I must now leave to the judgment of others to determine; 

 and it will be easy to see what variety of river may be suspi- 

 cious or insalubrious. We need not look for danger in a 

 rapid stream, a northern climate, or a hilly region ; but the 

 Ouse, the Lea, and similar rivers, cannot possibly be exempt, 

 unless England claims an exemption on some principle diffe-* 

 rent from that which exists in France and Italy. 



But to this I must add one remark. It is an universal pre- 

 judice in England that there is no hazard from running water ; 

 as it is, that clear water cannot be insalubrious, and that stag- 

 nation and putrefaction are essential to the production of 

 malaria. It would be fortunate, indeed, for France and Italy 

 were this true ; and fortunate for all the tropical climates, even 



