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- Description:
- One blueprint drawing entitled "U. S. Lake Survey, Detail of Intermediate Sweep Float." The drawing shows the design of a float (buoy) that was used as part of a sweep for obtaining water depth information. The sweep consisted of a line of 15 floats with flags, spaced at 100-foot intervals, that supported an underwater wire at a set depth. The line of buoys would then be dragged across an area of water by launches at each end of the buoy line. If the wire encountered any submerged obstructions, it would cause one or more float (buoy) flags to tip and thereby give an approximate location of an obstruction that could be investigated further. Such obstructions could then be plotted on the navigational charts that were produced by the Lake Survey Office. The plan is dated January, 1915.
- Date Issued:
- 1915-01-01T00:00:00Z
- Data Provider:
- Detroit Historical Society
- Collection:
- Maritime
