LAYING OUT DRAINS IN THE FIELD. 7S 



The field-book should have two more columns ruled 

 in addition to those described for simple levelling, one 

 for the elevation of grade line or simply '* grade line/* 

 {G.L.) and one for the depth of cut at each station 

 marked '* Cut. " These latter columns are for compu- 

 tations to be made after the field work has been com- 

 pleted. The accompanying specimen page of a field- 

 book gives an example of entries made in the field and 

 the subsequent computations for a short drain, 



A sketch plat of the lines should be made on the 

 right-hand page. This is very convenient and may with 

 proper care be made quite accurate by means of meas- 

 urements taken to certain landmarks or permanent 

 objects and by sketching in the angles and curves. 

 All of this can be done at the time of levelling without 

 retarding the work to any extent. Be particular to 

 note where branch lines of whatever kind enter other 

 drains. 



Notes for Platting', 



These should be taken at the same time the levelling 

 is done and recorded on the right-hand page of the 

 notes if it is expected that a plat better than the one 

 which can be made from the sketch will be required. 

 If do7ie with a compass^ locate all outlets of drains with 

 reference to some corner of the farm most prominent 

 or convenient by means of a measurement and bearing 

 from it. Take the bearings of the straight lines of the 

 ditch, and if a long curve is made, of several parts of 

 the curve so that it may be represented with reasonable 

 accuracy. Note where fence lines are crossed, and 

 make measurements from convenient stations to bound- 



