87 



(2) The work is done with materials — earth, water, etc., and 

 not with people. 



(3) Both the installation and the upkeep is directly under 

 the health officer, and the result cannot be vitiated by individual 

 carelessness, crankiness or bad faith. Compared with the in- 

 dividualistic methods, this one is like a municipality sterilized 

 water-supply compared with each individual sterilizing his own 

 drinking* water. The first gives the heaviest first cost, but is 

 the least troublesome and, to the community, the safest. It is 

 very generally applicable to villages and thickly settled com- 

 munities, less frequently to sparsely settled districts. The reason 

 is obvious. 



The expense of control of mosquitO' production in a com- 

 munity is roughly proportional to the area of breeding within 

 the limits of flight to the residences of that community. The 

 benefit of such control, and hence the funds allowabk to spend 

 on it, is proportional to the population It is obvious then that 

 the expense per head for this work increases and decreases in- 

 versely as the population per unit of area does. 



In practice, where we have tried it for villages and closely 

 settled communities, it has not proven costly — at least I hope 

 you will not think so for the results obtained. Let me give you 

 some figtires. 



I was asked this morning not to bring up Port Said or the 

 Canal Zone, so I will fall back on my notebook and give you 

 some from the United States and very recent. 



Roanoke Rapids, N. C, is a mill village, or rather several 

 mill villages, of over 4,0001 population. Prior to the malaria 

 work, the population was continually changing; wages were 

 good, work abundant and people came, but they develpoed 

 malaria and would not stay. The mill managers estimated the 

 efficiency of their employees as from 40 per cent, to 60 per cent, 

 during the four unhealthful months. During this time machines 

 were constantly idle. The mill physicians, who attended em- 

 ployees without charge, averaged during the summer months 

 for 19 1 2 and 19 13, fifty calls per day for malaria. The first 

 year of malaria work, 19 14 (control of mosquitoes was de- 



