2nd. Given a course which has been steered by compass to find the correct magnetic course made.-This is Question No. -Proceed thus: Place one leg of the dividers on the proceed to add This being an example of the third case, we first together the Easterly Bearings, which and the sum of the Westerly Bearings Proceed thus: amount to 27°, amounts to 75°. Gives N. 6° W. correct Magnetic Bearing. Next proceed to find the Deviations thus: : Bearings by Com- N.1°E. N.19°W. N.25°W. N.20°W. N.11°W, N.2°E. N.15°E. N.9°E. pass. 7 W. 13 E. 19 E. 14 E. Correct Magnetic N.6W. N. 6 W. N. 6 W. N. 6 W. N. 6 W. N. 6 W. N. 6 W. N.6W. Bearing. Deviations 5 E. 8 W. 21 W. 15 W. These deviations are now laid off on the accompanying Napier's diagram in the following manner: With a pair of dividers take 7° anywhere from off the centre line. Place one leg of the dividers on N. on the centre line, and the other leg on a dotted line running through N. (towards the left, the deviation being W.), and make a mark thus (') The deviation for N.E. is 13° E.; then with the dividers, measure off 13°, and lay off on a dotted line running through N.E. (towards the right, deviation being E.), and make another mark thus (*) Proceed in the same manner with the other deviations, taking care always to lay them off on a dotted line. Also lay deviation for N. off again at the foot of the diagram as well as at the top. Then join all the marks thus obtained by a flowing curved line running through all of them. Having now finished the curve, we proceed to answer No. 8 Question, which is given as follows: No. 8.-With the deviation as above, give the Courses you would steer by the Standard Compass to make the following Courses correct magnetic. Correct Magnetic Courses S. E. West. North. ANSWER.-Compass Courses S. 13°E. N. 70°W. N. 51°E. First place one leg of the dividers on S. E. on the centre line, extend the other along a line passing through S. E. parallel to a plain line until it reaches the curve at A. Keep the leg that is on A. quite still and move the other off S. E. until it cuts the centre line at B. The course there indicated, namely, S. 13° E., is the course to steer in order to make S. § E. correct magnetic. Proceed in a similar manner with the other two courses, West and North, and obtain N. 70° W., and N. 54° E. These answers must be written below those courses given in No. 8 Question. No. 9.-Suppose you have steered the following Courses by the Standard Compass, find the Correct Magnetic Courses made. ..... Compass Courses N. W. S. E. N. 60° W. S. 1° W. To get these answers proceed thus:-Place one leg of the dividers on W. by N., extend the other to the curve but along the dotted line passing through W. by N. to C. Keep the leg on C and move the other off W. by N. until it cuts the centre line at D. The course there indicated, namely, S. 82° W. is the correct magnetic course made by steering W by N. by the Standard Compass. Proceed in a similar manner with the other two courses N W. and S E. and find N 60° W and S 1° W. These answers must be written below those courses given in No. 9 question. No. 10.-You have taken the following bearings of two distant objects by your Standard Compass; with the ship's head at West by Standard Compass, find the Correct Magnetic Bearings. ANSWER.-Correct Magnetic Bearings N 16° W. S 43° W. The deviation to be applied to these two bearings is the deviation for the direction of the ship's head at the time when those bearings were taken, therefore proceed to get the deviation for West by placing one leg of the dividers on West, extending the other along the dotted line running through West to the curve. The space between the two legs of the dividers is the amount of deviation (Westerly) to be allowed on each of the compass bearings. Keeping the legs of the dividers the same distance apart, place one of them on N E., and the other upwards on the centre line (the deviation being Westerly); this will give N 16° W. as the correct magnetic bearing, corresponding to N E. bearing by standard compass. For the other, take the same deviation and lay it off upwards on the centre line from S S E. and obtain S 4340 E., the Correct Magnetic bearing corresponding to SS E. bearing by Standard Compass. These Correct Magnetic bearings must be written below the compass bearings given in question No. 10. I. 1. In the following table give the correct magnetic bearing of the distant object, and thence the deviation : Correct magnetic bearing, Ship's Head Bearing of distant Ship's Head Bearing of distant Deviation by Standard object by Standard required. by Standard object by Standard Deviation required. Compass. Compass. Compass. Compass. With the deviation as above, give the courses you would steer by the Standard Compass to make the following courses, correct magnetic. Correct magnetic courses, N.N.E., E. by N., W. S., S.E. Compass courses, Supposing you have steered the following courses by the Standard Compass, find the correct magnetic courses. made from the above deviation table. Compass courses, S.W. by W., S. 45° E., E. † N., N.W. Magnetic courses, You have taken the following bearings of two distant objects by your Standard Compass as above; with the Ship's head at West, find the bearings, correct magnetic. Compass bearings, S.W., East, N. 15° W. Bearings magnetic, |