70 



MOSQUITO ERADICATION 



roots to be encountered, extra ditches to care for seepage outcrops, 

 widths of ditches or streams, etc., must be considered in estimating 

 costs. Go along each water-course and its branches, estimate the 

 lengths by pacing, mark them on the map and note at the same time your 

 estimated cost of such brush-clearing, regrading, ditching, etc., as^is 

 necessary, step by step. Where ponds, marshes and other wet places 

 necessitate the installation of new ditches, indicate them on the map, 

 and enter in your notes the extent and cost of each. 



(Photos by E. B. Johnson, C.E.) 

 Fig. 50. — Brushing streams. The objects are to improve fish control, facilitate 



inspection and eliminate shade. 



"On flat territory during dry periods, it is frequently difficult to judge 

 of the amount of water that may stand intermittently on the land, and it 

 is advisable to note the character of the vegetation and make frequent 

 inquiry of the native population. If you can get a man well acquainted 

 with the locality to accompany you, so much the better. 



"When the mapping of all breeding-places and collections of water is 

 concluded and the data collected, sum up the different classes of excava- 

 tion, brushing, etc., and make an itemized statement thereof to accom- 

 pany the report of the survey. Determine the local cost of kerosene and 

 oil, delivered, find out, if necessary, what transportation could be ob- 

 tained from the town for oil distribution, ascertain whether ditches and 

 soil would warrant use of a ditching plough, what size ditching gang is 

 necessary and what number of men will be needed for oiling and main- 

 tenance (of ditches and streams). As a rule, the brushing (clearing) of 

 one bank of a ditch (or stream) is sufficient for oiling and inspection 

 purposes." 



