TimeTravel2

Time & Travel continued

The magnetic compass began as a simple needle that pointed north when floated in a bowl of water. By 1620, the free-floating “compass rose” card (showing 32 points of the compass with a fleur-de-lis for the North), with the needle glued to the underside of the card, was common. The compass would be suspended by gimbals (which allow the compass to remain horizontal even if the ship is not!) in a wooden box and covered with glass for protection from the elements. An experienced navigator, observing winds and tides, and logging course and speed, could use a compass to estimate a rough position at sea.


The compass contained within this wooden box dates from around 1850 but in design, in construction and in use it varies little from the compass that would have been used aboard the Mayflower.		The compass, covered with glass for protection from the elements, is suspended by gimbals (which allow the compass to remain horizontal even if the ship is not!).		The free-floating “compass rose” card (showing 32 points of the compass with a fleur-de-lis for the North), with the needle glued to the underside of the card.

This process was known as “dead reckoning.” During each 4-hour “watch,” the navigator would use a traverse board to track, in half-hour intervals or “bells,” two very important pieces of information: in what compass direction had the vessel traveled and at what speed.

The traverse board was a flat board, approximately 12” tall by 8” wide, with a compass rose painted on it. The rose was encircled by 8 rows of holes corresponding to the 32 directional points of the compass (256 holes in all). Beneath the compass rose and its 8 rows of encircling holes, was another set of 8 straight rows of holes, 8 or 9 across (between 64 and 72 holes in all).

The 256 encircling holes were used to record direction. At the end of each “bell” (measured by a half-hour sandglass), the navigator would note the vessel’s compass direction. A peg was then put in the first circle of holes at the directional point toward which the compass had been pointed during that first half hour. A second peg was put in the second circle of holes at the next “bell” to record the direction the compass had been pointed during that second half hour, and so on for each half hour during the watch.

The 8 straight rows of holes below the compass rose were used to chart the speed of the ship. The crew would estimate the speed of the ship by dropping a “chip log” (a special board attached to a long “log line”) over the stern and letting it pull out the log line for a minute’s time, as measured by another sandglass. The log line had a series of knots tied in it; each knot that was paid out marked a (nautical) mile per hour. When the speed was ascertained at the end of the first bell, a peg was put in the appropriate hole in the first row (using, for example, the 4^th hole in the row to indicate 4 knots) and so on for each bell in the watch.

At the end of the 4-hour watch, there were 8 directional pegs and 8 speed pegs in the traverse board. The navigator used this information to chart the ship’s progress on a sea chart. He then made a straight line from the position at the end of the previous watch to show how far along the desired course the ship had gone.