AND MARSHY SITUATIONS. 137 



The opinion that thofe difeaies, are the produtt of 

 fpecific matter generated by vegetable putrefadtion, ap- 

 pears to be rendered groundlefs from the dileafe varying 

 in its type and fymptoms, in proportion to the extent 

 and putridity of the foil, ftate of climate, feafon and 

 weather with refpecl to heat, moilture, «Scc. and alfj, in 

 its not being contagious, the reverfe of which is the cafe 

 with all known difeafes that are derived from fpecific 

 ma^ter. 



We are affured by the accurate Monro, in his account 

 of the difeafes which prevailed in the military hofpitals 

 in Germany, in 1761 and 1762, that the intermitting 

 fever feldom attacked any but thofe whofe folids had been 

 previoufly relaxed by the preceding heat of the fummer, 

 except when they had been fatigued and overheated 

 by the fun and afterwards expofed to the evening 

 dews. 



Dr. Lind of Windfor, fays, fudden expofure to cold 

 occafioned either an inflammatory fever or a fimple in- 

 termittent at Bengal, according to the predifpofition of 

 the body. 



The fcurvy as well as the difeafes already enumerated 

 alfo appears to derive its exiftence from a deficiency 

 of pure a.r in conjundlion with a cold and moid atmo- 

 fphere, a id a diet of falted flelh meats. For it generally 

 prevails in long voyages after a continuance of wet weather. 

 The hatches being kept Ihut at fuch times, prevents ven- 

 tilation, in confequence of which the oxygen becomes 

 exhaulled. 



Captain Cook in his two laft voyages preferved his 

 crew from the fcurvy by frequent ventilation, conftant 

 cleanlinefs, fuitablecloathing, and fl:ri£t difcipline. 



Dr. Trotter affures us that in a flave Ihip of which he 

 was furgeon, the feamen that were conftantly on deck, 

 and fed with the ordinary fea diet remained free from 



the 



