.On Malaria. 61 



transported from a distance by the winds, not generated on the 

 spot, it is found, perennially, and through the whole course of 

 successive years, to occupy certain places, and to avoid, as 

 constantly, others quite near, and, as far as the eye can judge, 

 equally exposed, and in all respects similar. Thus, one side 

 of a small garden, one side of a street, or one house, will be 

 for ever exposed to disease, or uninhabitable, when, at a few 

 feet or yards distant, the very same places are as constantly 

 free of danger : and thus it was found at the village of Faro, 

 in Sicily, that all the troops of our army quartered on one side 

 of the single street which formed it, were affected by fevers, 

 and suffered great mortality, while those on the other remained 

 in health. 



But the most remarkable case of this nature known to me, 

 is a domestic one, and which rests on the testimony of thou-^ 

 sands of persons, or of the whole country, however incredible 

 it may appear. It is, that between Chatham and Brighton, 

 including every town and single house, and Sittingbourne 

 among the rest, the ague affects the left hand side of the turn- 

 pike road, or the northern side, and does not touch the right 

 side, though the road itself forms the only line of separation. 



We cannot as yet conjecture the cause of this very singular 

 circumstance or property, at least in cases of this nature; 

 though, under certain events of this kind, there are some facts 

 in meteorology that may offer a solution. These are the 

 notorious ones, that a hoar frost, or a dew, will sometimes be 

 found most accurately limited, both vertically and horizontally, 

 by a definite line ; stopping, for example, at a particular hedge, 

 and reaching to a certain altitude on a tree : but for the other 

 cases, we must yet wait for a period of more accurate know- 

 ledge as to this singular substance. 



There is now one circumstance of importance, relating to 

 the destruction or decomposition of malaria, which must not 

 be passed over, from the interest of the facts depending on it: 

 this is, that its propagation is checked by the streets of a 

 crowded town, and apparently owing to this very cause, decom- 

 position. Thus it is observed, that the fever never appears in 

 the Judaicum of Rome, and, similarly, that the crowded streets 

 and the poor people escape, when the opulent houses and open 



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