Photograph as originally submitted to this page
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Caption: Marker detail: Two-pole Chain & Log Line
Additional Description: Two-pole Chain —
A common surveying tool used to measure distance in poles or rods. A standard surveying chain was 66 feet long and was composed of one hundred links each 7.92 inches long; 80 chains equals a mile. A pole is an old unit of measurement, 16-1/2 feet long. The captainsí two-pole chain thus was 33 feet long and had fifty links; it was useful only for measuring short distances.
Log Line —
Sailors commonly used a log line to determine the speed of their ship and from that, calculate the distance traveled A log line consisted of a piece of wood, the “log” and a rope, knotted at uniform intervals. The line was fastened to the ship and the log heaved overboard As the line paid out, one sailor counted the number of knots that slipped past in 30 seconds as timed by a sand glass. The number of knots paid out in that time was the speed of the ship in “knots.” Lewis and Clark carried a log line but rarely used it because they always were moving against or with a current of variable speed.
Submitted: January 3, 2019, by Cosmos Mariner of Cape Canaveral, Florida.
Database Locator Identification Number: p459327
File Size: 0.683 Megabytes
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