60 On Malaria, 



determined in a particular direction, or confined to a particular 

 spot, while it is a piece of knowledge of some practical value. 

 There is an appearance of incredibility about many of these 

 facts, and, accordingly, they have not only been disbelieved 

 but ridiculed, although nothing in the whole history of this 

 substance is better established. 



With respect to direction, in the first place, it is remarked in 

 Italy, currently, that this poison will enter the lower stories of 

 houses, particularly with open windows, when the next above 

 escape; and hence, in many places, no one ventures to sleep 

 on ground floors ; and the truth of this was confirmed in the 

 barracks at Jamaica by Dr. Hunter; as the cases of fever 

 occurring among the men in the lower rooms much exceeded 

 those which happened in the upper ones. But I am also in- 

 formed, that in some places in Norfolk this peculiarity is 

 reversed ; or that there are houses where it is remarked that 

 the ground-floors are safe, while no one can sleep in the upper 

 stories without hazard. 



That malaria may in some manner be attached to the soil 

 is also well known by its effects, and especially in Italy. There 

 it is remarked that it is extremely hazardous to cut down cer- 

 tain bushy plants which appear to entangle it, and that fevers 

 are a frequent consequence of such carelessness. Thus, also, 

 does fever seize on the labourers who may incautiously sit down 

 on the ground, while they would escape in the erect posture ; 

 being thus, indeed, sometimes suddenly struck with apoplexy, 

 which is one of the effects of this poison, or even with death. 



It has similarly been observed that it is often retained in the 

 shelter of drains, or in the ditches of fortifications; whence 

 frequent fevers among the sentries on particular guards, when 

 the other soldiers escape. And thus was it even proved at 

 Malta, that it was transported from the sea-shore, and thus 

 lodged in a dry ditch of the works at Valetta ; all these facts 

 being possibly to be explained, by supposing it possessed of a 

 greater specific gravity than the atmosphere, or else attached 

 to vapour thus weighty, exhibiting effects analogous to those 

 which carbonic acid displays in the Solfatara. 



But the circumstance most difficult of explanation is, that in 

 Rome, and numerous places in Italy, and even where it is 



