iSiS.] 



On Vaccination, 



ing the effects produced to their true causes, occasion of necessity 

 a great deal of uncertainty respecting the consequences deduced 

 from observations. A small number of facts similar to those 

 alleged can only produce probability. It is only by their great 

 number and their constancy that presumption is changed into 

 certainty. In order to appreciate the facts alleged against vacci- 

 nation, vi^e must compare them with the nature and the sum of 

 the established facts which have rendered the general opinion 

 ! . favourable to it. 



Some of the facts alleged against the cov/-pox have been bor- 

 rowed from the work of Dr. Woodville, entitled, Report on ike 

 Cow-pox, published at London, in 17^9, and translated the same 

 year into French by M. Aubert. The late M. Chappon collected 

 in 1803, in a work entitled, Traite Historique des Dangers de la 

 Vaccine, every fact which had been stated as unfavourable to the 

 new operation. We find there some remarkable facts which we 

 shall examine; but the greater number of them consist in asser- 

 tions without details and without proofs, which seem to have 

 been collected Vv^ith less judgment than prejudice. The author 

 himself, convinced at last of the insufficiency of his proofs, pub- 

 lished a retraction of his opinion, which he addressed to the 

 authors of the Journal de Medecine, published by MM. 

 Corvisart, Le Roux, and Boyer, and which at his request was in- 

 serted in the number of that Journal for September, ] 807, torn. 6, 

 p. 238. Other facts have been published in different books^ 

 most of which have been collected and examined by tbe authors 

 of the Bihliotheque Britannique, We shall notice such of them 

 as deserve to be known. Several observations have been com- 

 municated to ourselves in particular. Almost all those which we 

 had an opportunity of verifying were occasioned by false or inac- 

 curate reports. The rest offered only facts not very remarkable^ 

 and the consequences of which were equivocal. No observation ^' 

 can be of any weight except when it is accompanied by the ne- 

 cessary researches respecting the origin of the virus, respecting 

 the conditions characteristic of the cov/-pox, respecting its form, 

 its dei^elopement and its effects, respecting the phenomena Vv'hich 

 have followed it, and respecting the state of the person vaccinated. 

 For our parts we have not intentionally neglected a single fact of 

 any value which has come to our knowledge. 



We shall compare with these facts, 1. The results of the cor- 

 respondence of the Society established at Paris, under the aus- 

 pices of government in 1804, under the title of the Society for 

 the Extermination of the Small-pox. This society having col- 

 lected the papers of the central committee of vaccination formed 

 in 1799, when vaccination was introduced into France, and hav- 

 ing joined to it a very active correspondence, continued to the 

 present time_, the knowledge which it has acquired of the effects 



