Dec. 15.] THE NEW ZEALAND GAZETTE. 3841

MAGNETISM AND ELECTRICITY INCLUDING THE MAGNETIC COMPASS.

Paper 6 (3 hours).

1. The ship’s head having been swung to the eight principal points
   of the compass the following were the bearing of a distant
   object :—
   Ship’s N NE E SE S SW W NW
   Head
   Bearing. N³E N¹²W N¹⁸W N¹⁴W N¹¹W N⁸W N²E N¹⁰E
   Find the values of the approximate coefficients A, B, C,
   D, and E ; determine the deviations for the 9 points of the
   N.E. quadrant of the compass, and describe in detail how you
   would utilize your knowledge of the coefficients in adjusting
   the compass.

2. Is the direction of the ship’s head, when building, of any practical
   value to a compass adjuster ?
   Give full reasons for your answer.

3. The compass having been adjusted in the English Channel, H.F.
   1·0 Dip. 63°, coefficient B — 10° was corrected by 12 in. of
   3 in. diameter Flinders bar and a permanent magnet 24 in.
   from the compass needles.
   Later, off Cape Verde, H.F. 1·6 Dip. 25°, a deviation of
   3° W. developed on Westerly courses.
   Find what alteration should be made in the amount of
   Flinders bar and in the position of the permanent magnet
   to properly adjust Coefficient B. (N.B.—Ignore coefficient
   E and possible Gaussin error.)

4. If 40 ft. of wire ·04 in. thick has a resistance of 3 ohms, find the
   resistance of 1,000 ft. of wire of the same metal ·06 in. thick.

5. Why is a zinc-copper couple more effective than a zinc-iron couple
   when dilute sulphuric acid is the exciting liquid in a simple
   voltaic cell ?

6. Explain clearly the regular and irregular changes in Magnetic
   Variation.

7. What relation has the power of a permanent correcting magnet
   in a binnacle, and its distance from the compass card, upon the
   deflection caused ?

8. A compass needle 5 cm. long and whose poles are of unit strength
   lies in the magnetic meridian. Variation 45° E.
   A disturbing magnet of same length and strength as the
   compass needle is introduced lying in the true meridian Blue
   end North, its centre being 10 cm. East (true) from the centre
   of the compass and in the same horizontal plane. Calculate
   the initial moment, clockwise or anti-clockwise, tending to
   deflect the compass.

CONSTRUCTION, WORKING, AND UPKEEP OF SHIPS.

Paper 7 (3 hours).

1. What information is usually given in the Register of a Registration
   and Classification Society ?
   What is the object of this register ?

2. What special provision is made in coasting vessels which are required
   to load aground ?

3. Show by sketches the structural arrangements in a double bottom
   tank, having floors on alternate frames.

4. What is the object of inclining the light ship ? Describe the
   experiment and state the conditions necessary to ensure
   accurate results ?

5. What is Synchronism ? How and why should it be avoided ?

6. The half ordinates of a vessel’s waterplane are 0·1, 6·7, 9·5, 10,
   10·2, 10, 9·8, 8·8, and 1·8. Common interval 16·2 ft.
   Calculate tons per inch immersion.

7. Show that for small angles of heel the position of the Metacentre
   is determined by the Moment of Inertia of Waterplane and the
   Volume of Displacement, i.e. :—
   BM = I/V.

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