314 On Malaria. 



The lands are productive and assiduously cultivated. Salt marshes 

 occur on the sea shores frequently, and on the margins of small bays, 

 which indent tlie coast. In June and July of 1828, the fall of rain 

 was not far from the average of preceding summers, but much of it 

 fell in showers, and the rapid alternations of rain and sunshine were 

 followed by very luxuriant vegetation. In August, a little more than 

 an inch of rain fell before the 5th, and to this succeeded a drought for 

 the remainder of the month. The mean heat of the month was 73° 

 45', though it was occasionally as high as 91° Fahr. The margins 

 of ponds were soon laid bare, the rank and macerated herbage was 

 every were exposed to the unclouded rays of the sun, and the salt 

 marshes yielded their co-operation. Various forces conspired to in- 

 crease the energy and extent of pestiferous influences. For example, 

 the greater amount of surface and materials exposed, gave out a larger 

 quantity of poison, and that more concentrated ; the mitigating efliect 

 of rain was also needed to absorb or dilute the miasmata, or, by keep- 

 ing the ponds full, to secure the surfaces and materials usually under 

 water, from the chemical action of heat. Whether this theory is or 

 is not correct, the event was, that in this month a remitting bilious 

 fever endemic in many villages, became rapidly and extensively 

 epidemic, including all the open country ; sudden attacks seized the 

 most healthy, and those who in the spring had been affected with 

 fever and ague, found their relapses of a malignant character ; and 

 great mortality ensued. On the western verge of this tract is situ- 

 ated a town containing ten thousand inhabitants, and although the 

 epidemic came almost to the doors, and the sick were in every house, 

 and almost in every apartment in neighborhoods not half a mile distant, 

 yet not a single case occurred in the town, excepting a few persons 

 who had been in the country, and who after their return were visited 

 with fever. The site of the town is on table land about eighty feet 

 above the level of the sea, but not high enough to secure it from the 

 winds blowing over the adjacent country. It seems probable that it 

 owed its safety to the fires, smoke, and other counteracting, though 

 unknown causes, which accumulate wherever there is a numerous and 

 industrious population. The sickness did not abate until the commence- 

 ment of frost, which is another proof of the truth of the position that frost 

 extinguishes the malarious principle, and another reason for suppos- 

 ing it referable to a vegetable origin. But if malaria is subdued by 

 frost, the question arises, why do complaints proceeding from it oc- 

 cur in winter ? To this inquiry, Dr. Keate's report of those regi- 



