OF THE MARSH POISON. 295 



uniform, in pi-oportion to the power of the remote exciting 

 cause, that the varying types of fever might be measured al- 

 most to a certainty by the degrees of solar heat, as marked on 

 the thermometer. Thus it is most rare and uncommon to 

 meet with an ague in the West Indies in the swampy alluvial 

 plains at the level of the sea, where the generality of the towns 

 and settlements are placed ; — as rare, or rather as impossible, 

 as it would be to meet with any thing else but a common re- 

 mittent or an intermittent fever, on the cooler mountain mar- 

 shy levels of the same country. The highest degree of suscep- 

 tibility and excitement from solar heat on the part of the sub- 

 ject, combined with the highest state of preparation from the 

 same, on the part of the agent, appear to be essential in all si- 

 tuations to the production of the dreadful yellow fever, which, 

 luckily for mankind, is incapable of being transported to any 

 locality of lower temperature, or texture of soil different from 

 that which gave it birth. Need I say, that such a disease, 

 however rapid and appalling may be its epidemic current, is 

 not, and cannot, no more than the common ague or remittent 

 fever, be in the smallest degree contagious. 



There are very few, indeed, of those that have been compel- 

 led to live under its scourge, who have not overcome the pre- 

 judices of their education on this head ; but, unluckily, a dif- 

 ferent impression obtains very generally amongst those who 

 have never seen the disease, which deeply affects the peace of 

 society every where, and in some countries has proved subver- 

 sive of the best interests of humanity. Such opinions, it is the 

 duty of every man, who has had sufficient experience, to com- 

 bat, by stating the results of personal exposure and investiga- 

 tion, and thereby do his utmost to rescue medical science 

 from the dominion of a prejudice which disgraces it. 



VOL. IX. p. II. p p r 



