213 ADDITIONAL NOTES ON CONTAGION. 



feeling and external appearance of health, passing to leeward, within six feet of other per- 

 sons just recovered from the malignant pestilential fever, and wearing the clothes they 

 had on their persons during the presence of the fever, have received the contagion of the 

 fever from them, and have perished under its action ; if this has happened in the open ait 

 (wherein nothing generally conceived to be impure, could be perceived) surely your 

 definition cannot be said to accord with experience. Again, if in a chamber kept as clean 

 and as pure as it is possible to keep a sick chamber, the disease has been in many hundred, 

 I might safely say thousand, instances, communicated from the persons afflicted with it, 

 to others in a state of apparent health, when the latter have approached the former to 

 within the radius of contagion ; if this is true, and the proofs of its being so are innume- 

 rable, I must again say, that surely your definition cannot be said to accord with expe- 

 rience. Had it been advanced, indeed, that all pyrexious contagions, but particularly 

 that of the malignant pestilential (yellow) fever, are rendered more violent in their ac- 

 tion under the circumstances you have stated, no possible objection could be made to the 

 proposition, because it is supported and proved by all experience ; and the reason is, per- 

 haps, as obvious as the fact itself is generally admitted. It does not proceed from the 

 impure atmosphere becoming assimilated to the poison introduced, but from rendering the 

 system of the healthy person, who receives the poison by approximation to the sick, more 

 susceptible, at the moment of its introduction, of its peculiar action; or the chemical 

 physician may say, had it been advanced that the atmosphere of the sick chamber, be- 

 ing confined and close, as it too often is, is rendered obnoxious to health, by having its 

 oxygen diminished by the respiration of the persons, sick and well, inhabiting it, and that 

 thereby the effluvia of contagion become more concentred by being less subjected to 

 decomposition or solution, whichever you will, the proposition would be less objection- 

 able. But in either case, the laws of the existing contagion are not affected ; in the one, 

 the healthy person is only made more susceptible of its impression ; in the other, it be- 

 comes less volatile, and therefore more virulent, and more certain of infecting. But the 

 atmosphere is not assimilated to its principle. And, indeed, it must be evident, that 

 were this not the fact, we should have no right to expect a specific disease produced by 

 a specific contagion — plague and yellow (malignant pestilential) fever produced by the 

 contagions peculiar to them. 



But all fevers appearing in the circumstances you mention, would necessarily have an 

 undefined character; they would be universally anomalies; a result so inconsistent with 

 the regularity of nature, I imagine, has never been met with. There are, indeed, seem- 

 ing anomalies produced by a combination of morbid causes and effects. But as these are 

 well known to depend on the irregular performance of some particular functions, occa- 



