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CHAPTER II.

THE COMPASS. THE LEAD. THE LOG.

The Compass. A piece of steel which has been touched by a magnet, if free to move on a pivot, will point in a definite direction. To this direction, as a standard, all others may be referred, and any desired course thus followed.

The Mariner's Compass is based upon this principle. It consists of the needle, which is attached to the under side of a card, Fig. 1, representing the horizon, and graduated with the thirty-two "points" of the compass. The North end, or pole, of the needle is fixed under the North point of the card. The needle and card are balanced on a pivot fixed vertically in the compass-box, or bowl, and the whole is protected by a glass covering. The bowl is filled with a liquid composed of 45% pure alcohol and 55% distilled water. This mixture remains liquid at a low temperature exceeding -10° Fahrenheit.

As the North mark of the compass-card always points with the needle to the North, the other marks will of course point to their respective parts of the horizon.

The variation of the compass and its local errors are not noticed here, as they may be referred to in any book on Navigation.

The Lubber's Point is a vertical line drawn on the inside of the bowl of the compass to correspond with the vessel's head; the point of the card coinciding with it shows the course steered, or the direction in which the ship is heading.

To Box the Compass is to name the points in regular succession, beginning at one point and ending at the same; thus, commencing with north and going around with the sun, say :—

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Each point is further divided into half-points and quarter-points, and the fractional points are named upon the same principle as the points themselves; thus:

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A quarter-point (or half-point) can obviously be named with reference to either one of the nearest whole points. Thus N. E. would be defined also as N. by E. & N., and E. N. E. E. would be recognized as E. by N. N.

The following are the usual rules for naming quarterpoints:

1st. From East or West to the nearest whole point, use for quarter-points that name which ends with the word North or South. Thus, E. 1 S., not E. by S. & E.

2d. From N. E., N. W., S. E., or S. W., to the nearest whole point use that name which ends with the nearest cardinal point. Thus, N. E. N., not N. E. by N. E.; N. W. W., not N. W. by W. 3 N.

3d. In all other cases use that name of the quarter or half-point which ends with the word East or West. Thus, E. S. E. E., not E. by S. S.

A Dumb Compass is used at the mast-heads, taffrail, &c., for taking relative bearings. It consists of a compasscard painted on a board or cut on a copper plate.

Relative Bearings. In referring to the position of an object, the direction of the wind, &c., with reference to the ship, use is frequently made of what are called relative bearings, instead of giving the directions in compass-points.

In Fig. 2, Plate 9, a ship is represented as heading North. A lighthouse or other object if seen bearing North would also be said to bear, from that ship: Ahead.

If seen bearing N. by E.: One point on starboard bow. Bearing N. N.E.: Two points on starboard bow. Bearing N.E. by N.: Three points on starboard bow. Bearing N.E.: Broad off starboard bow.

Bearing N.E. by E.: Three points forward of starboard beam.

Bearing E. N. E.: Two points forward of starboard beam. Bearing E. by N.: One point forward of starboard beam. Bearing East: Abeam.

Bearing E. by S.: One point abaft starboard beam. Bearing E. S.E.: Two points abaft starboard beam. Bearing S. E. by E.: Three points abaft starboard beam. Bearing S.E.: Broad off starboard quarter.

Bearing S.E. by S.: Three points on starboard quarter. Bearing S. S.E.: Two points on starboard quarter. Bearing S. by E.: One point on starboard quarter. Bearing South: Astern.

And similarly at N. by W., N. N. W., &c., one point on port bow, two points on port bow, &c., &c.

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To find the direction of the wind, when ship is close hauled. A square-rigged ship, when close hauled, can usually lie no nearer the wind than six points; therefore, if a ship be close hauled on the starboard tack, and her head at North, count six points thence to the right hand, or towards East, and you will find the wind at E. N.E. The wind then forms with the keel an angle of six points, so that if a line at Fig. 2, Plate 9, represents the ship's keel, (c) will be the yard when braced up, and (d) the direction of the wind. In practice the yard is braced up sharper, to make the sail stand to better advantage.

When the ship is on the port tack with her head North, the points are counted on the opposite or left side, and the wind is W. N.W. If the ship's head be put to any point of the compass, counting six points to the right or left hand, according as the ship is on the starboard or port tack, will always give the direction of the wind when the vessel is close hauled.

When the wind is E. by N., in Fig. 2, the ship is then one point free, because her head is seven points from the wind. With the wind East in the figure, it is said to be two points free, or abeam, as shown in the remarks on relative bearings. If the wind is at S. in the figure, it is said to be aft.

After learning to box the compass with the sun, go around against the sun, or from North towards West, and practise with such questions as the following: Ship on the port tack, heading S. W. W., how will she head on the other tack? With the wind at S. W. and steering due East,

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