178 NOTES AND ILLUSTRATIONS. 



celebrated Dr. Chisbolm and Dr. Haygarth, whose respective writings on the malignant 

 yellow fever are monuments of the learning and talents of their authors, and may be pro- 

 nounced the most able and satisfactory works in support of the doctrines which they have 

 espoused; as the writings of our late distinguished countrymen, Doctors Rush and Mil- 

 ler, may be referred to as containing the best summary of the theories which these authors 

 have embraced. 



Although the specific nature of the matter by which certain diseases are propagated is 

 still imperfectly understood, yet it were idle to deny the existence of contagion ; and 

 it is certain we have recently ascertained, in no inconsiderable degree, the laws by which 

 it is governed. " In the present state of medical knowledge," says the Edinburgh Re- 

 view, " it would not, we conceive, be at all more absurd to deny the existence of fever 

 altogether, than to maintain that it is not propagated by contagion." Review of Dr. 

 Haygarth 1 s Letter to Dr. Percival. 



An attempt was made by the late Dr. Richard Bayley, of New-York, to establish a 

 distinction between contagion and infection, and to discriminate the diseases arising from 

 these two different sources. (Treatise on the Yellow Fever of New-York, 1795.) This 

 distinction has been adopted by some European physicians, and, among others, by Dr. 

 Joseph Adams, but without the due acknowledgment. 



About the year 1797, Dr. Mitchill promulgated his ingenious doctrines on the pesti- 

 lential fluids; and in 1804, Dr. Edward Miller made public his Attempt to Deduce a 

 Nomenclature of certain Febrile and Pestilential Diseases from the origin and nature of 

 their remote cause. Medical Repository, vol. 1. 8r 7. 



In July, 1808, a new theory on the laws governing the communication of contagious 

 and infectious diseases, was published by Dr. Hosack, in a letter addressed to Dr. Colin 

 Chisholrn. (Vide Edin. Med. and Surg. Journal, vol. 5.) Dr. Hosack admits the 

 distinction proposed by Dr. Bayley to approach nearer the truth than any other that had 

 hitherto been offered, but he does not consider it as presenting a view of the whole truth. 

 Those diseases which are communicable from one person to another, and are generally 

 considered of a contagious or infectious -nature, are distributed by Dr. H. into three 

 classes. First, such as are communicated exclusively by contact ; as itch, syphilis, sib- 

 bens, Laanda of Africa, frambsesia, elephantiasis, variola vaccina, and hydrophobia : second- 

 ly, such as are communicable by contact and the atmosphere; as small-pox, measles, chick- 

 en-pox, hooping-cough, scarlatina, and cynanche maligna : thirdly, those diseases generally 

 communicable only in an impure air ; as plague, yellow fever, typhus, in its various forms, 

 and dysentery. 



