this case), and place them, with their differences, in the following order:

This complied with, take, with a pair of dividers, 2° 19.3' from the scale of longitude, or base line a b, and lay off this distance on each of the perpendiculars from the base line, and through the points e, e thus obtained, draw the parallel of 32°. In like manner, from the parallel of 32°, lay off the next meridional difference 2° 22.4', and through the points f and thus obtained, draw the parallel of 34°. Proceed similarly with the remaining meridional differences and get the positions of the parallels of 36°, 38°, 40°, and 42°; through the points g, h, k, and c and d thus found, draw lines to represent the respective latitude parallels. Divide the last parallel c d into degrees and minutes, the same as the parallel of 30°, and draw the meridians 61° to 73°, inclusive. On Plate I, the meridian of every other degree only is drawn, in order not to crowd the chart. The result will be as shown on Plate I, representing a chart on Mercator's projection according to the limits required. The principal points are now marked down according to their latitude and longitude, and the coast line is carefully drawn in by hand.

48. If, in the foregoing illustration the required latitude had been from 30° to 42° south, the construction would have been exactly the same with the exception that the base line ab should then have been drawn at the top of the paper, and the meridional difference laid off in the opposite direction, that is, from c to a and from d to b.

From the foregoing, it is evident that by the aid of a table of meridional parts, the construction of charts on Mercator's