78 



MOSQ UI TO ERA DICA TION 



connection with previous construction by: Drainage or filling of borrow 

 pits and low areas where practicable; proper provision for drainage 

 (in a sanitary sense) behind embankments and fills across valleys; 

 replacing to true gradient of culverts where necessary; drainage or other 

 provision for care of over-flow waters at tanks and towers; clearing of 

 weeds and refuse at regular intervals (supplemented by oiling, if needed) 

 from right-of-way ditches, especially in and adjacent to settlements. 

 (b) "New Construction Conditions. — Consideration of sanitary features 

 in connection with new construction works ; that is prevention or correc- 

 tion of conditions menacing the health, especially of settlements and 



Fig. 52. — A culvert properly placed; it is neither too low nor to< 



can form about it. 



high. Xo pool 



communities. To this end, consultation should be had with the sani- 

 tary or medical departments before construction is begun. Preference 

 should invariably be given to sanitary works which will influence as 

 large a number of individuals as possible." 



OTHER POSSIBLE SOURCES OF AID 



The same considerations apply, in large measure, to street 

 and road departments. 



Industrial plants often, through carelessness or ignorance, 

 cause conditions favorable to mosquito-breeding. Cisterns and 

 fire-barrels may be unscreened or untreated, water may be 

 allowed to enter under the buildings, drainage may be neglected, 

 processes that may with little cost be modified may cause 

 abundant breeding. 



Private individuals may have large problems in swamp areas, 

 in swimming, recreation or fish ponds, cess-pools, etc. 



In all the above-mentioned cases, the director should call on 



