Correct the Courses for Variation and Leeway, and find the Latitude and Longitude in, and the Course and Distance made good by Inspection. The first True Course is found by reversing W.N.W. the bearing; that is, making it E.S. E., and allowing 2 points to the right for Variation. The next Course is found by allowing 1 point to the right of N. by W. for Leeway, and then 2 points to the right for Variation. To find the Distance for this Course, sum up the tenths, and as they make ten, carry 1 to the Knots; this 1 added up with the Knots makes the distance 21. The last Course is got from the Current. Correct the Courses for Deviation, Variation, and Leeway, and find the Lat. and Long. in, and the Course and Distance made good by Inspection. Lat. left 43° 55' N. DIFF. LAT. DEPARTURE. True Courses. Dists. Diff. lat. 2 4 S. North. South. East. 51 N. To find the first true Course.-Reversing the bearing we have S.S.E. E.; now, looking in the log for ship's head S.S. E., we find pt. E. deviation, and allowing pt. to the right of S.S. E. E. we have S.S. E.; and then allowing the variation 2 pts. to the left of S.S. E., we have S. 4 E. the true course. PARALLEL SAILING. Add together the log. secant of the Latitude, Table 25 (subtracting 10 from the index), and the log. of the Departure, Table 24; the number corresponding to the sum of these logs., Table 24, will be the Difference of Longitude: In Latitude 12° 10′ the Departure made good was 126 miles. Find the Difference of Longitude by Parallel Sailing. Latitude 12° 10' secant (-10), Table 25, .0.009866 add. Diff. of Long. 128.9 miles, Table 24, ... log. 2.110236 In Latitude 48° 49′ the Departure was 120.5 miles. Required the Diff. of Long. by Parallel Sailing. 1. In Latitude 36° 36' the Departure made good was 160 miles. Find the Difference of Longitude by Parallel Sailing. 2. In Latitude 52° 52′ the Departure made good was 108 miles. Find the Diff. Long. by Parallel Sailing. 3. In Latitude 36° 50' the Departure made good was 48 miles. Find the Diff. Long. by Parallel Sailing. 4. In Latitude 47° 49' the Departure made good was 128 miles. Find the Diff. Long. by Parallel Sailing. |