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gg, Aer Habitabii^is. J, F. Siefvert, 1759. 



The comprehenfive nature of the fubjed, and 

 the concife manner in which the hiftory of the air 

 is treated in this dilTertation, rpnder it impoflit>le 

 %o give a proper abftradl in our confined plan. 

 This element is here confidered in all the various 

 changes to which it is fubjeft , its properties un- 

 der the different and oppofite alterations difcuffed ; 

 its effeds on the earth in the various quarters of 

 the globe ; and its influence on the health and eco- 

 nomy of life, and manners of the inhabitants. 



1. With refpedl to its heat and cold in the diffe- 

 rent quarters of the earth : of thefe the general re- 

 fult is given according to the computation of the 

 Swedijh thermometer, or Celjius^s^ in which (o) is 

 the point of congelation, and (100) that of boil- 

 ing water ; five degrees in this being equal to nine 

 of Farenheifs. 



2. Its drynefs and tnotfture^ and the general effedls 

 of thofe qualities pointed out. The torpid ftate of 

 the inhabitants of hot countries during fummer: 

 heat in thofe countries defoliates trees, as cold does 

 in temperate climes. 



3. Its gravity^ and the different degrees and 

 leifeds of it confidered, 



4. The effeds of the different winds ^ and their 

 falutary and pernicious tendencies. That of Calms 

 alfo. In the I fie of St. Thomas there 'is a dead 

 calm for two months, during which the worft 

 difeafes prevail. 



5. The effeds of an hot atmofphere farther il- 

 luflrated by the ftate of the Indians, Difeafes 



r thereby produced in more moderate climates. 



6. T^mper^te 



