COMETAEY INFLUENCES. 



varies from one to six days, and its force is always very moderate. 

 A fog, thick enough to render the disk of the sun red, always 

 accompanies this wind. The particles deposited by this fog upon 

 the leaves of vegetables and on the black skin of the natives 

 appears always white, but the nature of this whitish matter was 

 not ascertained. It was remarked that this fog was speedily 

 dissipated by the sea; for although the wind was sensible on 

 sea at many leagues from the coast, the fog became rapidly less 

 dense, and, at the distance of little more than a league, it disap- 

 peared. 



"One of the characteristics of this wind and fog is extreme 

 dryness. When it continued for any time, the foliage of the 

 orange and lemon trees exposed to it became shrivelled and 

 withered. So extreme is this dryness,- that the covers of books, 

 even when closed, locked in chests, and enveloped in linen cloth, 

 were curved by it just as if they had been exposed to the heat of 

 a strong fire. The panels of doors and frames of windows, and the 

 furniture, were often cracked and broken by it. Its effects upon 

 the human body were not less marked. The eyes, lips, and palate 

 were parched and painful. If the wind continued unabated so 

 long as four or five days, the face and hands grew pallid. The 

 natives endeavoured to counteract these effects by smearing their 

 skin with grease." 



Considering all these effects, it might be naturally inferred that 

 the Harmattan must be highly insalubrious ; yet observation 

 proved it to have the extreme opposite quality. It was found 

 that its first breath completely banished intermittent fevers. 

 Those who had been enfeebled by the practice of excessive bleeding, 

 then prevalent there, soon recovered their strength. Epidemic 

 and remittent fevers, which had a local prevalence, disappeared 

 as if by enchantment. But the most wonderful effect of this 

 atmospheric phenomenon was, that it rendered infection incom- 

 municable, even when applied by artificial means, such as inocu- 

 lation. 



There was at Wydah, in 1770, a British slave ship called the 

 Unity, having on board a cargo of above 300 negroes. The small- 

 pox having broken out among them, the owner resolved on inocu- 

 lating those who had not taken the natural disease. All those 

 who were inoculated before the commencement of the Harmattau 

 took the disease, but of seventy that were inoculated on the 

 second day after its commencement, not one took the infection ; 

 yet after the lapse of some weeks, when the Harmattan ceased 

 these seventy negroes took the natural disease. Soon after they 

 were attacked by it, the Harmattan recommenced, and the disease 

 almost immediately disappeared. 

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