178 LAND DRAINAGE 



spond with the elevations as determined from the readings 

 for the same drain in Table XV. 



233. Recording reading taken, in feet and inches. - 

 When scales graduated to feet, inches, quarters, eighths, 

 and sixteenths are used, the writer has found it most 

 satisfactory to read and record all fractions of the inches 

 in terms of eighths only. For example : 



-^Q inch = J eighth inch. 



-J- inch = 2 eighths inch. 



f inch = 4 eighths inch. 

 YQ inch = 3J eighths inch, 

 -j-f inch = 6| eighths inch. 



Three feet 7y^ inches are recorded in the table as 

 3-7-6J. 



In practice, one quickly becomes used to this plan of 

 expressing values and recording them, and finds little 

 difficulty in using them in making his computations. 



Table XX is a reproduction of level readings as ]they 

 appear in notes for two drains 300 feet and 250 feet in 

 length, respectively. Note in columns 3 and 4 the rela- 

 tive positions in the column of (1) the figures expressing 

 feet, (2) those expressing inches, and (3) those express- 

 ing the fractions of an inch (always expressed in eighths 

 of an inch). 



234. Relation of values. An eighth of an inch is a 

 trifle more than one one-hundredth of a foot (.0104). A 

 sixteenth of an inch is a little more than five thousandths 

 of a foot (.0052). When one works as close as one- 

 sixteenth of an inch, in ordinary drain work, one is doing 

 well, and this is closer than can be done with the ordinary 

 cheap drainage level. One can, with care, work to one- 

 sixteenth of an inch with the hose-level. 



