Required the course and distance from A to B in each of the following examples, by Rule 1, or Mercator's method: Required also the compass courses in examples 82, 83, and 84, the variation of compass being 2 points E., and deviation as in table, p. 16. See Rule (k). To find the latitude and longitude in, having given the Course and Distance. Rule 2. (1). To find latitude in. Add together log. cos. course * and log. distance, the sum (rejecting 10 in the index) will be log. true difference latitude, which find in the tables; reduce to degrees and minutes, and place the letter N. or S. against it, according as course is northward or southward. (2.) Apply true difference latitude to latitude from, so as to get the latitude in. (Rule e.) (3.) To find longitude in. Take out the meridional parts for the two latitudes, and get M. D. Lat. (Rule b.) (4.) Add together log. tangent course and log. meridional difference latitude; the sum (rejecting 10 in the index) will be the log. difference longitude, which find in the tables; reduce to degrees and minutes, and place the letter E. or W. against it, according as the course is eastward or westward. (5.) Apply difference longitude to longitude from, so as to get longitude in. (Rule f.) EXAMPLES. 85. Sailed from A, N. 37° 10' E., 472.6 miles; required the latitude and longitude in. * Take out, at same opening of tables, log. tan. course and place it a little to the right. A ship in latitude 27°0' S. and longitude 123° W. sailed S.S.E.E., 150 miles: required the latitude and longitude in. Required the latitude and longitude in, by Rule 2, or Mercator's method, in each of the following examples, having To find the course and distance by Middle Latitude method. Rule 3. (1.) Find the true difference latitude, middle latitude, and difference longitude (a), (c), (d). (2.) To find the course. Add together log. cos. mid. lat. and log. diff. long., and from the sum subtract log. true difference latitude; the remainder is the log. tan. course, which find in the tables, and mark it with the same letters as the true difference latitude and difference longitude. From the same opening take out the log. secant of course. (3.) To find distance. To the log. secant course just found, add the log. true difference latitude; the sum (rejecting 10 in index) will be the log. distance. EXAMPLES. 92. Required the course and distance from A to B, by Required the course and distance from A to B in each of the following examples, by middle latitude method: To find the latitude and longitude in, having given the course from a given place, and distance. * (1.) To find latitude in. Add together log. cos. course and log. distance; the sum (rejecting 10 in the index) is * Take out at the same time log. sin. course. C the log. true difference latitude, which find from tables, and mark N. or S. according as the course is northward or southward. Apply true difference latitude (turned into degrees and minutes, if necessary) to the latitude from, and thus get latitude in. (Rule e.) Find the middle latitude. (Rule c.) 2. To find longitude in. Add together log. sin. course, log. distance, and log. secant middle latitude; the sum (rejecting 20 in the index) is the log. difference longitude, which find in tables, and mark E. or W. according as the course is eastward or westward. Apply the difference longitude (in degrees and minutes) to the longitude from, and thus get longitude in. (Rule f.) EXAMPLE. 96. Sailed from A, S. 37° 10′ W., 472.6 miles; required the latitude in and longitude in (by middle lat. method). Required the latitude and longitude in, by middle latitude method, in each of the following examples, having sailed |