. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 34 BULLETIN 512^ U. S. DEPARTMENT OF AGRICULTUEE. a hoe who digs a hole at each position of the rod to serve as guides to the plowman who follows immediately and lays out the first furrow. This is the cheapest and most satisfactory method of laying out level terraces. Several terraces may be laid out from one position of the instru- ment, depending upon the vertical interval and length of the rod. If the entire length of the terrace can not be seen from one position of the level, the rodman should retain the rod at the
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 34 BULLETIN 512^ U. S. DEPARTMENT OF AGRICULTUEE. a hoe who digs a hole at each position of the rod to serve as guides to the plowman who follows immediately and lays out the first furrow. This is the cheapest and most satisfactory method of laying out level terraces. Several terraces may be laid out from one position of the instru- ment, depending upon the vertical interval and length of the rod. If the entire length of the terrace can not be seen from one position of the level, the rodman should retain the rod at the last point visible, the instrument should be moved to a new position, and a reading of the rod taken. This reading should be used in locating points on the terrace line from the new position of the too-—. iiiiiiHiiiiiHiim Fig. 15.—System of level-ridge terraces on a field having irregular slopes. The graded terrace is more difficult to lay out than is the level terrace, because the rod readings never are the same for any two points on the terrace line. The first point on the terrace line is found in a manner similar to that described for the level terrace. Assuming that the terrace drains to one outlet, then a fall will occur from the middle of the terrace line toward the outlet and a rise in the other direction. If, for instance, a grade of foot per hundred feet be used, and if guide stakes are to be set 50 feet apart where the alignment is fairly straight and 25 feet apart on bends, then for each 25 feet in distance toward the outlet a fall of foot would be required, and, therefore, for each 25 feet in the direction of the outlet the rod reading should be increased foot. The distance should be measured with a tape. If a variable grade is used the rod readings should be computed Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of the
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