Attack by Drainage 123 



scheme that prevents a possible failure due to 

 improper or neglected inspection, or which 

 abolishes the personal equation, is worthy of 

 consideration. 



The engineer often has another point of view. 

 He plans the ditches for rapid removal of storm 

 water, but gives no thought to the condition of the 

 ditch between showers, and seldom has any interest 

 in or responsibility for the future success of the 

 mosquito drainage work. The sanitary officer in 

 charge may be replaced by a man inexperienced 

 in Anopheles control. The engineer who planned 

 the work may be in another part of the world and 

 probably has not designed his drainage scheme to 

 meet these conditions. In general, he tries to be 

 rid of a body of standing water at the lowest first 

 cost. To him the problem is very simple, and 

 apparently not worth much consideration. He 

 may not be interested in the habits of mosquitoes 

 and is generally ignorant of the fact that small 

 puddles or even a fraction of an inch of water left 

 standing will defeat the sanitarian's object. He 

 may not care if the water in the ditches runs 

 rapidly enough to remove Anopheles larvas, but in 

 the tropics the width of the bottom of a ditch often 

 determines whether it is to be a means of reducing 

 Anopheles or of producing an additional supply. 



