. Drainage of farm lands. Drainage. 8 UNIVERSITY OF SOUTH DAKOTA. front end of the boat and one in the middle of the rear end, hold the boat steady while the boom is being swung about. Such a float- ing dredge begins work at the upper end of the ditch and requires sufficient water to float it as it excavates along on its course down the ditch line. A three and one-half yard machine at work in Illinois is shown in Fig. 2. This machine will excavate ditches varying in width from fifteen to seventy-five feet, and in depth from three to fifteen feet. The section of ditch which a floating dipper dr
. Drainage of farm lands. Drainage. 8 UNIVERSITY OF SOUTH DAKOTA. front end of the boat and one in the middle of the rear end, hold the boat steady while the boom is being swung about. Such a float- ing dredge begins work at the upper end of the ditch and requires sufficient water to float it as it excavates along on its course down the ditch line. A three and one-half yard machine at work in Illinois is shown in Fig. 2. This machine will excavate ditches varying in width from fifteen to seventy-five feet, and in depth from three to fifteen feet. The section of ditch which a floating dipper dredge will excavate is somewhat the form of the letter U as shown in Fig. 3. It is impossible for an excavating machine of this type to make side slopes less than one-half horizontal to one vertical and true and uniform. Neither can it dig true to grade. The sides will be more or less rough and irregular and the grade of the bottom of the ditch will vary from three to twelve inches below the true grade. The contractors usually excavate the ditch larger and deeper than required so that when the low places are filled in by the deposition of silt and fine de- bris, the ditch will acquire a uniform cross-section of at least the capacity required by the specifications. The form of the ditch after a few seasons of erosion and weathering is shown in Fig. 4. The cost of excavation depends on the amount of yardage and. /^/a^- Sect/or? of f/jc/fay Ore eye, Oiib t? after- <sros/o/7 ar?d ^ conditions, and varies from seven to fifteen cents per cubic yard. (d) The scraper dredge of the Page bucket type consists of a hull or boat with machinery similar to that used on a floating dredge. On the front end of the boat are two booms or cranes,. 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 McDaniel, Allen Boyer,
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdrainag, bookyear1910
