Sect. III.] Theory and Practice of PJnjsic. 5G I 



The comparative mildness and infrequency of 

 pestilential diseases in Christian Europe, durin^i^ 

 the late century, are probably owing to a combina- 

 tion of many causes. Much may ])e srifely ascribed 

 to improvements in the cleanliness and vcntiiation 

 of houses, in diet, in apparel, in habits, customs, 

 and all the modes of life. Cities, which are usually 

 the great nurseries of pestilence, are now less 

 crowded than in former ages. The comforts, de- 

 <:encie% and elegancies of life, from a variety of 

 causes, are now enjoyed by a greater portion of the 

 .community, and in a much higher degree than in 

 preceding times. To the same causes, also, may 

 be ascribed the almost entire banishment of that 

 loathsome disease the Leprosy, from tlie civilised 

 world, which has been in a great measure etfected 

 in the course of the last a^e. 



The frequent and mortal prevalence of the pesti- 

 lential disease called Yellow Fever, in the cities, 

 and in some parts of the country, in the United 

 States, for the last ten years, forms a memorable 

 €vent in the medical history of this country, during 

 the century which is the subject of this retrospect. 

 The malignity and ravages of this epidemic impress^ 

 .ed the public mind with the deepest apprehensions, 

 and undoubtedly gave a new impulse and vigour to 

 medical investigation. The origin of this disease 

 has been warmly contested in the United States, 

 in the West-Indies, and in Europe. AVliile many 

 maintain that it is produced by the exhalations of 

 putrefaction, whether such putrefaction be found in 

 the fdth of cities, of marshy grounds, or of vessels 

 f)i\ the water ; others, on the contrary, assert, that 

 it is always produced by contagion emitted from 



