On Malaria^ 53^ 



added to this cause, the effects must be expected to increase 

 in a sort of geometrical ratio ; almost leading to the fear that 

 the whole city itself may, in time, fall a victim to it, or be- 

 come abandoned to the wolves and mosquitoes. 



If I dare not inquire more minutely in|o the remaining cir- 

 cumstances connected with the propagation of malaria, lest I 

 should extend this article to an inconvenient length, it is 

 necessary now to offer some remarks on prevention, and espe- 

 cially as it relates to this circumstance — the propagation of the 

 poison ; since the rules for prevention, as far as this relates to 

 production, may be deduced from what was said in a former 

 paper on this subject, and relate chiefly to the drainage of 

 lands, and to other practices, more or less obvious, which a 

 little reflection will, without much difficulty, deduce from what 

 was there said. 



It is plain, in the first place, that as far as the winds are 

 concerned, it is by opposing obstacles to their course that we 

 must attempt to counteract or divert their influence ; and that, 

 in this case, it is through the use of trees alone that we possess 

 any power. Thus reversely, as in the case just stated, the 

 cutting down of trees and forests has often been a serious 

 cause of diseases in certain countries, by admitting a malaria 

 to particular spots; though it is easy to see that where any 

 given spot suffers from malaria, through condensation or con- 

 finement, the clearing away of these would be the remedy, by 

 attaining a free ventilation. To detail the particular modes in 

 which remedies may be applied through this species of aid, is 

 obviously unnecessary, and not easy, as it must depend on 

 local circumstances, differing for each place ; but I may re- 

 mark, as an example in illustration of my meaning, that where, 

 as in many of the narrow and prolonged valleys of Greece, the 

 sea shore is a marsh, the remedy would be to plant a screen of 

 trees beyond it, and thus to prevent the sea winds from passing 

 into the interior. And thus did the ancient Romans compel 

 the planting of trees on the shores of Latium, to check the 

 current from the Pontine marshes; rendering groves sacred, 

 under heavy penalties, and enacting other laws with the same 

 intentions. 



With respect to such temporary precautions in these cases 



