. Agricultural engineering; a text book for students of secondary schools of agriculture, colleges offering a general course in the subject and the general reader. Agricultural engineering. CHAPTER XII LEVELING AND GRADING TILE DRAINS Taking Levels. After the drains have been staked, levels should be taken with an instrument on the grade stake at each station and recorded in the field book. This is the process of leveling which has been mentioned in a previous chapter. Notes for each line, be it main, submain, or lateral, should be kept under an appropriate title or head, and all the levels sh
. Agricultural engineering; a text book for students of secondary schools of agriculture, colleges offering a general course in the subject and the general reader. Agricultural engineering. CHAPTER XII LEVELING AND GRADING TILE DRAINS Taking Levels. After the drains have been staked, levels should be taken with an instrument on the grade stake at each station and recorded in the field book. This is the process of leveling which has been mentioned in a previous chapter. Notes for each line, be it main, submain, or lateral, should be kept under an appropriate title or head, and all the levels should refer to a common datum. If the instrument is pro- vided with a compass, the bearings of the line should be record- ed on the right hand side of the note book beside the level notes. A good system of notes is shown in the specimen pages from a field book found in Part I. The Grade. The amount of slope given to tile drains is called the grade and is stated in several ways. The more common way is to give the change in elevation of the drain for every hundred feet of length. It is also stated as the percentage the change of elevation is of the length. Thus 73. Fig. 50. Taking levels in making a Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Davidson, Jay Brownlee, 1880-1957. St. Paul, Minn. , Webb Pub. Co.
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