4^ On Malaria* 



cloud, and often of very small dimensions, will remain at rest 

 in the atmosphere, or travel very many miles without the loss 

 of its integrity; however we may imagine it assailed by the 

 various meteorological causes of destruction, as well as by me- 

 chanical violence. This in itself proves the consistency with 

 which a current of wind preserves the relative positions of its 

 integral parts; because it is plain that a disturbance among 

 these must disturb or destroy the cloud which, in reality, forms 

 a portion of that current, as a gaseous body: and since that 

 cloud is a mist, since it might have been the very evening mist 

 embodying a malaria, and since it is its real vehicle and repo- 

 sitory, it is plain that had it, or any individual cloud, contained 

 such a portion of malaria, it must have had the power of trans- 

 mitting that, and would actually have transported it to any 

 distance to which itself might travel. Thus, it is evident, may 

 a fog, generated in Holland, carry without difficulty to the 

 limits of its range, or to the coast of England, that malaria 

 which became entangled with it at its birth-place or in its 

 passage; and thus, I have little doubt, is the fact of those 

 agues explained, and this transportation to such distances 

 established. 



I cannot, at least, conceive any demonstration as to facts of 

 this nature more convincing, nor anything wanting to the proof; 

 while I may proceed to make some remarks on the east wind, 

 and on fogs, simply, because they concern this question. 



The proof that it is a malaria in the fog, and not the fog 

 itself, which is the cause of disease, is evinced by the following 

 fact; while it ought surely to be unnecessary to say, that if 

 fog alone could produce such fever, water itself must be the 

 poison : since a fog is a cloud, and its constituents, when pure, 

 are only atmospheric air and water. No intermittents are ever 

 produced on the western or northern shores by the sea fogs, 

 and for the plain reason, that there is no land whence they 

 arrive. The clouds of mountainous regions do not produce 

 fevers, though these also are fogs; and what forms a most 

 absolute proof of this is, that in Flanders, it is the fogs which 

 come with a southwest wind, or the southerly winds themselves, 

 which transport and propagate malaria and disease ; while, as 

 soon as the winds shift, and blow from the sea, the fevers dis- 



