Meteorological Observations for 1793. 109 



5. The north- west wind is allowed to be the most 

 healthy that blows over this continent. Some years 

 it is by far the most prevalent. This year the wind 

 came in all 



124 days from the south-west, 

 84 days from the north-west, and 

 72 days from the north-east. 



It is the opinion of many persons, that the yellow- 

 fever, if not imported, is always the offspring of vege- 

 table putrefaction, in or near the district of country 

 where it breaks out. A rainy season, followed by a 

 long drought, and hot weather, causes such putrefac- 

 tion ; and has, therefore, in every climate, been pro- 

 ductive of diseases ; unless the heat was so intense, 

 or of such long duration, as wholly to dissipate mois- 

 ture ; or, the country was so circumstanced as imme- 

 diately to drain itself. None of these exceptions apply 

 to Pennsylvania, where the climate is upon the whole 

 temperate, and the soil in many parts but little drained 

 and improved. Yet the heat is here at times as great 

 as in the West- Indies ; and, in the opinion of respec- 

 table writers, our summers are sometimes equally 

 capable of generating contagious fevers, though their 

 progress, they say, may, by the use of proper means, 

 be easily stopped. During the nine years Mr. 

 Reichel has spent in Nazareth, there never has been 

 so much rain in the spring and early part of the sum- 

 mer, as last season ; nor was the heat in former years 

 so uninterrupted and oppressive to the human frame, 

 as that which succeeded in the months of June, July, 

 August, and September. 



