280 ON THE NATURE AND HISTORY 



extinction by the periodical rains of the winter season, not, 

 however, without some exultation, and self-congratulation, on 

 the greater comparative mortality that occurred amongst the 

 stranger soldiers than amongst themselves. 



From all the foregoing, it will be seen, that in the most un- 

 healthy parts of Spain, we may in vain, towards the close of 

 the summer, look for lakes, marshes, ditches, pools, or even ve- 

 getation. Spain, generally speaking, is then, though as prolific 

 of endemic fever as Walcheren, beyond all doubt one of the 

 driest countries in Europe, and it is not till it has again been 

 made one of the wettest, by the periodical rains, with its ve- 

 getation and aquatic weeds restored, that it can be called heal- 

 thy, or even habitable, with any degree of safety. 



During the years 1815, 1816, and 1817, I was employed in 

 making a topographical health survey of all the West India 

 colonies, which afforded me opportunities, in that diversified, 

 dangerous, and active climate, of improving the observations I 

 had elsewhere made upon pestiferous miasmata, of a kind that 

 I could scarcely have anticipated. 



It might there be seen, that the same rains which made a 

 deep marshy country perfectly healthy, by deluging a dry well 

 cleared one, where there was any considerable depth of soil, 

 speedily converted it, under the drying process of a vertical 

 sun, into a hot-bed of pestiferous miasmata. Thus, in the 

 Island of St Lucia, the most unwholesome town of Cas- 

 tries, at the bottom of the Carenage, which is altogether em- 

 bosomed in a deep mangrove fen, became perfectly healthy 

 under the periodical rains ; while the garrison, on the Hill of 

 Morne Fortune, immediately above it, within half cannon shot, 

 began to be affected with remittent fevers. The two localities 

 within this short distance evidently changed places in respect 



to 



