Latitude left 49° 57'N. Latitude left 49° 57'N. Latitude in 39 20 N. Latitude in 39 #. N. Diff. of Latitude 10 37 Sum of Lat. 89 17 N. 60 -----——— Middle Lat. 44 38 In Miles 637 90 3. Draw the Meridian A D, from A to D set off the Difference of Latitude 637 Miles, and on D, ered the Perpendicular D G, which make equal to the Departure 789 Miles. Draw the Line AG, and that will be the Distance 1014 Miles, and the Angle D A G the Course 51° oss. Again, draw E K parallel to A D, making the Distance from A D equal to the Departure D G 789, take the Complement of the Middle Latitude 45° 22' in your Compasses from the Line of Chords, and set that .# on the Arch on the opposite Side of the Meridian A D, through where that cuts the Arch, draw the Line A E, to cut the Linek; in E, from E, let fail the Perpendicular E B, i. it is done, for A E will be the Difference of Longitude 1109 iles. Is to Radius 90° 10.ooooo Is to the Departure 789 2.89708 So is Departure 789 2.89708 So is Radius 90° io.ooooo 12.897c8 - 12.89708 2.80414 9.891 or To find the Difference of Longitude it will be, As Co-Sine Middle Latitude 44° 38' 9.85225 Is to Departure 789 2.89708 So is Radius 90 IO.OOOOO 12.897.08 9.85225 First. The Extent from the Difference of Latitude 637 to the Departure 789 on the Line of Numbers, will reach from Radius, or 45° backward to 51° os' the Course on the Line of Tangents. Secondly. The Extent from 51° 5' to Radius or 90° on the Line of Sines will reach from the Departure 789 to the Distance 1014 on the Line of Numbers, Thirdly. The Extent from the Complement of Middle Latitude, #. 22' to Radius or 90° on the Line of Sines, will reach from the eparture 789, to the Difference of Longitude IIo9, on the Line of Numbers. One Latitude, Course, and Distance, given, to find the Difference of With the Course and Distance, find the Difference of Latitude and Departure, as in Case I. in Plane Sailing : viz. draw the Meridian A D, and on A describe an Arch with the Chord of 60°, and upon it set off the Course S. E. by S. or 3 Points, through where that cuts the Arch draw the Line A C, making it equal to the Distance 591, from C, let fall the Perpendicular CD, then will CD be the Departure, and A D the Difference of Latitude 491 Miles. Draw the Line E F Paralkel to AD, making the Distance from it equal to the Departure. . Take the Com. of Mid. Lat, 51° 36' from the Line of Chords in K. Compasses, and set it off on the Arch on the other Side of the seridian A B, and through where that cuts the Arch, draw the Line A E, to cut the Line E F in E, from E let fall the Perpendicular ED and it is done, for A E will be the Difference of Longitude, 419 Miles. - Lat. To find the same by CAlculation. " To the Diff. of Lat. 491.4 2.69144 To the Departure 328.3 2.51633 To find the Difference of Longitude. Without the Departure it will be, With the Departure it will be, First. ‘The Extent from Radius or 8 Points to the Complement of the Course, 5 Points on the Line marked S. Rhumbs, will reach from the Distance 591 to 491 the Difference of Latitude on the Line of Numbers.” Secondly. “The Extent from Radius or 8 Points to the Course 3 Points on the Line S. Rhumbs, will reach from the Distance 591 to the Departure 328 on the Line of Numbers.” 4. Thirdly Thirdly. “The Extent from the Sine Com. Mid. Lat. 51° 36' to Radius, or 90° on the Line of Sines, will reach from the Departure 328 to the Difference of Longitude 419 on the Line of Numbers.” |