FOURTH ANNUAL YEAR BOOK — PART VI. 449 



age district numbered and fastened together in book form in such a way 

 that any one sheet may be removed. In case of maps too large for one 

 sheet, sheet number one may show the entire district to a small scale, and 

 the large scale map may be made in sections on 18x24 sheets. The 

 writer uses this method in his sewerage practice and finds it perfectly 

 practicable. Applied to drainage it would aid greatly in systematizing 

 and preserving the records. 



For drainage ditches the engineer should prepare complete specifi- 

 cations covering all phases of the work, and a careful estimate of the 

 cosft, which it would be better to have a little too large than not large 

 enough. The engineer should advise in advertising for bids and award- 

 ing the contract. During construction his services will be constantly re- 

 quired. He must stake out the work, see that it is properly constructed, 

 calculate the number of cubic yards and the amounts due the contractors, 

 and perform many other duties of a responsible nature. 



In making drainage assessments the engineer's advice will have 

 great weight. Professor L. E. Ashbaugh, who has charge of the instruc- 

 tion in drainage for the students in civil engineering at the Iowa State 

 College, uses the following method: 



With map in hand the two commissioners and the engineer make 

 a careful inspection of the entire drainage district, and record for each 

 tract of forty acres (or less if owned by two or more parties), the quan- 

 tity of land therein of the following classes: swamp land, wet pasture 

 land, tillable land needing drains, and rolling land. While in the field, 

 the forty-acre tract can be quite closely subdivided. In the office these 

 subdivisions are tabulated and opposite each is placed the following 

 factors, first, for swamp land 100 per cent or two thirds, for pasture land 

 two thirds, tillable wet land one third, these amounts showing propor- 

 tions to be taxed on account of condition of land; second, factors aie 

 then placed showing proportional benefits due to proximity to the drain: 

 land through which the drain runs being assessed 100 per cent, while 

 land at some distance is placed at 70 per cent or 50 per cent, or what- 

 ever seem just; third, factors are similarly placed to show benefits di;e 

 to an outlet being provided, thus 100 per cent for land at upper end of 

 the drain and decreasing to a small amount at the outlet. The product 

 of the acreage of each subdivision into the factors just mentioned, gives 

 the proportional part which is assessed to each tract. 



The result of this method is: A property owner at some distance 

 from the drain does not pay as much as one who is directly benefited 

 by having the drain through his land. The man at the outlet pays little- 

 as compared with the one at the upper end who uses the entire length 

 of tile. Assessment is made with reference to need of drainage. A re- 

 view of records in your county auditor's office will show that oftimes 

 men at the outlet pay more than their entire expense would be if they 

 made a private drain, or that men a long distance from the drain psy 

 as much as those most directly benefited. 



In conclusion, the writer will call attention to the vest pocket 

 ''Drainage Engineering Notes." recently prepared for general distribu- 

 tion by the civil engineering department of the Iowa State College. A 



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